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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2018	Mar. 01, 2019	Jun. 30, 2018
Document and Entity Information
Entity Registrant Name	Quanterix Corp
Entity Central Index Key	0001503274
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 162.8
Entity Common Stock, Shares Outstanding		22,461,202
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 44,429	$ 79,682
Accounts receivable (less reserve for doubtful accounts of $36; including $48 and $123 from related parties as of December 31, 2018 and 2017, respectively)	6,792	5,599
Inventory	5,945	3,571
Prepaid expenses and other current assets	2,330	400
Total current assets	59,496	89,252
Restricted Cash	1,000
Property and equipment, net	2,923	1,874
Intangible assets, net	2,348
Goodwill	1,308
Other non-current assets	536	653
Total assets	67,611	91,779
Current liabilities:
Accounts payable (including $36 and $0 to related parties as of December 31, 2018 and 2017, respectively)	5,110	3,552
Accrued compensation and benefits	4,449	2,624
Other accrued expenses (including $226 and $170 to related parties as of December 31, 2018 and 2017, respectively)	3,129	3,560
Deferred revenue (including $33 and $1,182 with related parties as of December 31, 2018 and 2017, respectively)	5,437	4,942
Current portion of long term debt		5,036
Total current liabilities	18,125	19,714
Deferred revenue, net of current portion (including $0 and $1,074 with related parties as of December 31, 2018 and 2017, respectively)	520	1,709
Long term debt, net of current portion	7,623	4,346
Other non-current liabilities	278	144
Total liabilities	26,546	25,913
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value: Authorized-120,000,000 shares as of December 31, 2018 and December 31, 2017; issued and outstanding- 22,369,036 and 21,707,041 shares as of December 31, 2018 and 2017, respectively	22	22
Additional paid-in capital	216,931	210,196
Accumulated deficit	(175,888)	(144,352)
Total stockholders' equity	41,065	65,866
Total liabilities and stockholders' equity	$ 67,611	$ 91,779

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Consolidated Balance Sheets
Accounts receivable, reserve for doubtful accounts	$ 36
Accounts receivable, related parties	48	$ 123
Accounts payable, related parties	36	0
Other accrued expenses, related parties	226	170
Deferred revenue, current, related parties	33	1,182
Deferred revenue, net of current portion, related parties	$ 0	$ 1,074
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized shares	120,000,000	120,000,000
Common stock, shares issued	22,369,036	21,707,041
Common stock, shares outstanding	22,369,036	21,707,041

Consolidated Statement of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenue	$ 37,632	$ 22,874	$ 17,585
Cost of Goods Sold:
Total Costs of Goods Sold and Services	19,684	12,887	9,837
Gross profit	17,948	9,987	7,748
Operating Expense:
Research and development (including stock compensation of $513, $180, and $59 for the years ended December 31, 2018, and 2017, and 2016, respectively)	15,805	16,304	16,993
Selling, general and administrative (including stock compensation of $4,143, $1,912, and $851 for the years ended December 31, 2018, 2017, and 2016, respectively)	33,693	19,688	12,466
Total operating expenses	49,498	35,992	29,459
Loss from operations	(31,550)	(26,005)	(21,711)
Interest income (expense), net	46	(951)	(1,298)
Other (expense) income, net	(7)	(63)	(164)
Loss before income taxes	(31,511)	(27,019)	(23,173)
Income tax provision	(25)
Net loss	(31,536)	(27,019)	(23,173)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss	(31,536)	(27,019)	(23,173)
Accretion of preferred stock to redemption value		(4,110)	(4,437)
Accrued dividends on preferred stock		(59)	(8)
Net loss attributable to common stockholders	$ (31,536)	$ (31,188)	$ (27,618)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.43)	$ (8.30)	$ (12.89)
Weighted-average common shares outstanding, basic and diluted	21,994,317	3,756,954	2,142,840
Product revenue
Total revenue	$ 23,365	$ 14,124	$ 10,601
Cost of Goods Sold:
Total Costs of Goods Sold and Services	12,729	7,742	6,299
Service and other revenue
Total revenue	12,117	7,676	5,012
Cost of Goods Sold:
Total Costs of Goods Sold and Services	6,955	5,145	3,163
Collaboration and license revenue
Total revenue	$ 2,150	$ 1,074	1,972
Cost of Goods Sold:
Total Costs of Goods Sold and Services			$ 375

Consolidated Statement of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cost of product revenue, related party activity	$ 191	$ 235	$ 322
Stock compensation expense in cost of goods sold	228	76	18
Stock compensation expense in research and development expenses	513	180	59
Stock compensation expense in selling, general and administrative expenses	4,143	1,912	851
Product revenue
Related party revenue	294	339	509
Service and other revenue
Related party revenue	149	165	107
Collaboration and license revenue
Related party revenue	$ 2,150	$ 1,074	$ 172

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net loss	$ (31,536)	$ (27,019)	$ (23,173)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	1,352	482	444
Stock-based compensation expense	4,884	2,168	928
Non-cash interest expense	170	238	388
Gain on disposal of fixed assets	(14)		11
Non-cash research and development expense for issuance of warrants to a vendor			2,078
Change in fair value of preferred stock warrants		90	307
Changes in operating assets and liabilities:
Accounts receivable	(983)	(1,682)	(1,655)
Deposits			200
Prepaid expenses and other assets	(1,828)	(273)	6
Inventory	(1,603)	(2,043)	(526)
Other non-current assets	267
Accounts payable	1,318	1,003	1,131
Accrued compensation and benefits, other accrued expenses and other liabilities	1,101	2,035	1,200
Deferred revenue	(1,849)	2,895	919
Net cash used in operating activities	(28,721)	(22,106)	(17,742)
Investing activities
Purchases of property and equipment	(1,518)	(1,132)	(526)
Acquisitions, net of cash acquired	(3,801)		(300)
Purchase of investments	(150)
Proceeds from sale of assets	15
Net cash used in investing activities	(5,454)	(1,132)	(826)
Financing activities
Proceeds from sale of preferred stock, net of issuance costs		65,575
Proceeds from sale of common stock, net of issuance costs	(20)	8,423	45,428
Proceeds from exercise of stock warrants		29	18
Proceeds from stock options exercised	1,871	202	213
Proceeds from the issuance of notes payable and warrants, net of issuance costs		(59)	2,954
Payments on notes payable	(1,929)	(921)	(2,697)
Net cash (used in) provided by financing activities	(78)	73,249	45,916
Net decrease in cash and cash equivalents	(34,253)	50,011	27,348
Cash, restricted cash, and cash equivalents at beginning of period	79,682	29,671	2,323
Cash, restricted cash, and cash equivalents at end of period	45,429	79,682	29,671
Supplemental cash flow information
Accretion of redeemable convertible preferred stock to redemption value		4,110	4,437
Cash paid for interest	660	743	945
Warrants issued to lenders		119	128
Purchases of property and equipment included in accounts payable	78	74	72
Fair value of common stock warrants exercised and reclassified as shares of common stock	$ 196	$ 2,187	$ 5,257

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Common stock	Additional paid-in capital	Accumulated deficit	Series A Preferred Stock	Series B Preferred Stock	Series C Preferred Stock	Series D Preferred Stock	Total
Beginning balance at Dec. 31, 2015	$ 2		$ (88,642)	$ 23,898	$ 15,178	$ 34,369		$ (88,640)
Beginning balance (in shares) at Dec. 31, 2015	1,976,992			14,400,001	5,624,106	8,605,944
Increase (Decrease) in Stockholders' Equity
Issuance of stock, net of issuance costs							$ 45,428
Issuance of stock, net of issuance costs (in shares)							12,420,262
Exercise of preferred stock warrants				$ 3,901	$ 1,374
Exercise of preferred stock warrants (in shares)				1,300,000	397,530
Exercise of common stock options		$ 213						213
Exercise of common stock options (in shares)	90,883
Vesting of restricted stock (in shares)	247,621
Accretion of preferred stock to redemption value		(1,141)	(3,296)	$ 1,180	$ 907	$ 2,309	$ 41	(4,437)
Stock-based compensation expense		928						928
Net loss			(23,173)					(23,173)
Ending Balance at Dec. 31, 2016	$ 2		(115,111)	$ 28,979	$ 17,459	$ 36,678	$ 45,469	(115,109)
Ending Balance (in shares) at Dec. 31, 2016	2,315,496			15,700,001	6,021,636	8,605,944	12,420,262
Increase (Decrease) in Stockholders' Equity
Issuance of stock, net of issuance costs	$ 5	65,570					$ 8,423	65,575
Issuance of stock, net of issuance costs (in shares)	4,916,480						2,113,902
Exercise of preferred stock warrants				$ 2,078		$ 138
Exercise of preferred stock warrants (in shares)				700,000		31,283
Exercise of common stock options and vesting restricted stock		204						204
Exercise of common stock options and vesting restricted stock (in shares)	289,321
Cumulative-effect of adoption of ASU		141	(141)
Accretion of preferred stock to redemption value		(2,029)	(2,081)	$ 1,080	$ 840	$ 2,140	$ 50	(4,110)
Conversion of preferred stock to common stock	$ 15	143,319		$ (32,137)	$ (18,299)	$ (38,956)	$ (53,942)	143,334
Conversion of preferred stock to common stock (in shares)	14,185,744			(16,400,001)	(6,021,636)	(8,637,227)	(14,534,164)
Warrant Liability reclassified to equity upon IPO		823						823
Stock-based compensation expense		2,168						2,168
Net loss			(27,019)					(27,019)
Ending Balance at Dec. 31, 2017	$ 22	210,196	(144,352)					65,866
Ending Balance (in shares) at Dec. 31, 2017	21,707,041
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options (in shares)	16,718
Exercise of common stock options and vesting restricted stock		1,871						1,871
Exercise of common stock options and vesting restricted stock (in shares)	645,277
Common stock issuance offering costs		(20)						(20)
Stock-based compensation expense		4,884						4,884
Net loss			(31,536)					(31,536)
Ending Balance at Dec. 31, 2018	$ 22	$ 216,931	$ (175,888)					$ 41,065
Ending Balance (in shares) at Dec. 31, 2018	22,369,036

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity
Issuance of common stock in initial public offering, offering costs	$ 8,173

Organization and operations	12 Months Ended
Organization and operations	Dec. 31, 2018
Organization and operations
Organization and operations	1. Organization and operations Quanterix Corporation (NASDAQ: QTRX) (the Company) is a life sciences company that has developed next generation, ultra-sensitive digital immunoassay platforms that advance precision health for life sciences research and diagnostics. The Company’s platforms are based on our proprietary digital “Simoa” detection technology. The Company’s Simoa bead-based and planar array platforms enable customers to reliably detect protein biomarkers in extremely low concentrations in blood, serum and other fluids that, in many cases, are undetectable using conventional, analog immunoassay technologies, and also allow researchers to define and validate the function of novel protein biomarkers that are only present in very low concentrations and have been discovered using technologies such as mass spectrometry. These capabilities provide the Company’s customers with insight into the role of protein biomarkers in human health that has not been possible with other existing technologies and enable researchers to unlock unique insights into the continuum between health and disease. The Company is currently focusing on protein detection, but is also developing its bead-based technology to detect nucleic acids in biological samples. The Company currently markets the Simoa HD‑1, a fully automated immunoassay bead-based platform with multiplexing and custom assay capability, and related assay test kits and consumable materials. The Company launched a second bead-based immunoassay platform (SR-X) in the fourth quarter of 2017 with a more compact footprint than the Simoa HD‑1 Analyzer and less automation designed for lower volume requirements while still allowing multiplexing and custom assay capability. The Company initiated an early-access program for its third instrument (SP-X) on the new Simoa planar array platform in January 2019, with the full commercial launch planned for April 2019. This compact instrument has the ability to reach a 10 plex and has custom assay capability. The Company also performs research services on behalf of customers to apply the Simoa technology to specific customer needs. The Company’s primary customers are in the research use only market which includes academic and governmental research institutions, the research and development laboratories of pharmaceutical manufacturers, contract research organizations, and specialty research laboratories. The Company acquired Aushon Biosystems, Inc. (Aushon) in January 2018. With the acquisition of Aushon, the Company acquired a CLIA certified laboratory, as well as Aushon’s proprietary sensitive planar array detection technology. Leveraging its proprietary sophisticated Simoa image analysis and data analysis algorithms, the Company further refined this planar array technology to develop the SP-X instrument to provide the same Simoa sensitivity found in its bead-based platform. Initial Public Offering In December 2017, the Company completed its initial public offering (IPO) in which the Company sold 4,916,480 shares of its common stock at the initial public offering price of $15.00 per share The Company’s common stock began trading on The Nasdaq Global Market on December 7, 2017. The aggregate net proceeds received from the IPO, net of underwriting discounts and commissions and offering expenses, was $65.6 million. Immediately prior to the completion of the IPO, all then outstanding shares of convertible preferred stock were converted into 14,185,744 shares of common stock. The related carrying value of shares of preferred stock and warrants in the aggregate amount of $143.3 million was reclassified as common stock and additional paid-in capital. Additionally, the Company filed an amended and restated certificate of incorporation with the Secretary of State of the State of Delaware, effective December 11, 2017 to, among other things, change the authorized number of shares of common stock to 120,000,000 and the authorized number of shares of preferred stock to 5,000,000. Liquidity The Company has had recurring losses from operations since inception and has an accumulated deficit of $175.9 million at December 31, 2018 and the Company incurred a net loss of $31.5 million, $27.0 million, and $23.2 million for the years ended December 31, 2018, 2017, and 2016, respectively. Prior to the IPO the Company had funded its operations principally from issuances of preferred stock, debt financings, grants, product and service sales and development and license agreements. At December 31, 2018, the Company had $44.4 million of unrestricted cash and cash equivalents. The Company expects the current cash balance will be sufficient to fund operations for a period of at least one year from the date the consolidated financial statements are issued. There can be no assurances, however, that no additional funding will be required or that additional funding will be available on terms acceptable to the Company, or at all. Basis of Presentation The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification and Accounting Standards Update of the Financial Accounting Standards Board (“FASB”). The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, estimates related to revenue recognition, fair value of equity instruments, valuation allowances recorded against deferred tax assets, and stock-based compensation. Actual results could differ from those estimates. Reverse Stock Split On December 4, 2017, the Company effected a reverse stock split of its common stock at a ratio of 1‑for‑3.214. The shares of common stock subject to then outstanding stock options were adjusted accordingly to reflect the reverse stock split. All common stock and related per share amounts presented in these financial statements and related notes have been retroactively adjusted to reflect the 1‑for‑3.214 reverse stock split.

Significant accounting policies

12 Months Ended

Dec. 31, 2018

Significant accounting policies

Significant accounting policies

2. Significant accounting policies

Principles of consolidation

The consolidated financial statements have been prepared in accordance with U.S. GAAP and include the accounts of Quanterix Corporation, and its wholly-owned subsidiaries. All material intercompany transactions and balances have been eliminated in consolidation.

Use of estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. In making those estimates and assumptions, the Company bases its estimates on historical experience and on various other assumptions believed to be reasonable. The Company’s significant estimates included in the preparation of the consolidated financial statements are related to revenue recognition, fair value of equity instruments and notes receivable, fair value of assets acquired and liabilities assumed in acquisitions, valuation allowances recorded against deferred tax assets, and stock-based compensation. Actual results could differ from those estimates.

Revenue recognition

The Company recognizes revenue when (1) persuasive evidence of an arrangement exists, (2) shipment and installation, if applicable, has occurred or services have been rendered, (3) the price to the customer is fixed or determinable and (4) collection of the related receivable is reasonably assured. The Company primarily generates revenue from the sale of products and delivery of services, as well as under license and collaboration agreements. The Company’s product revenue includes the sale of instruments as well as assay kits and consumables which are used to perform tests on the instrument. The Company’s service revenue is generated from services performed in the Company’s Simoa Accelerator Lab under contracts to perform research services on behalf of customers and maintenance and support services.

Product revenue

Revenue for instrument sales is recognized upon installation at the customer’s location or upon transfer of title to the customer when installation is not required, which is generally the case with sales to distributors. In sales to end-customers, the Company provides the installation service and often payment is tied to the completion of the installation service. When installation is required, the Company accounts for the instrument and installation service as one unit of accounting and recognizes revenue when installation is completed, assuming all other revenue recognition criteria are met. Instrument transactions often have multiple elements, as discussed below. Included with the purchase of an instrument is a one-year assurance type product warranty assuring that the instrument is free of material defects and will function according to specifications. In addition, the sale of an instrument includes an implied warranty which is promised to the customer during the pre-sales process, at the time that the sales quote is issued to the customer. The implied warranty is provided over the same one-year period as the standard warranty. The services included in the implied warranty are the same as those included in the extended service contracts, and include two bi-annual preventative maintenance service visits, minor hardware updates and software upgrades, additional training and troubleshooting which is beyond the scope of the standard product warranty. The implied warranty has been identified by the Company as a separate deliverable and unit of accounting. Consideration allocated to the implied one year service type warranty is recognized over the one year period of performance as service and other revenue as described below. Consideration allocated to any other elements is recognized as the goods are delivered or the services are performed.

Service and other revenue

Service revenue includes revenue from the implied one-year service type warranty obligation, revenue from extended service contracts, research services performed on behalf of a customer in the Company’s Simoa Accelerator Lab, and other services that may be performed. Revenue for the implied one-year service type warranty is initially deferred at the time of instrument revenue recognition and is recognized ratably over a 12‑month period starting on the date of instrument installation. Revenue for extended warranty contracts is recognized ratably over the service period. Revenue for research and development services and other services is generally recognized based on proportional performance of the contract, when the Company’s ability to complete project requirements is reasonably assured. Most of these services are completed in a short period of time from the receipt of the customer’s order. When significant risk exists in the Company’s ability to fulfill project requirements, revenue is recognized upon completion of the contract.

Collaboration and license revenue

Collaboration and license revenue relates to the Joint Development and License Agreement (JDLA) with bioMérieux SA (bioMérieux) as amended and restated in December 2016 by the Amended and Restated License Agreement (the Amended JDLA) and the agreements with a diagnostics company. Refer to “Collaboration and License Agreements (Note 11)” for a description of these arrangements and the Company’s revenue recognition policies for these agreements. On September 6, 2018, bioMérieux notified the Company that it was terminating the Amended JDLA, forfeiting any future IVD licensing rights to Quanterix’ Simoa technology and enabling Quanterix to consolidate and regain control of all Simoa IVD licensing and IP rights. As a result of the termination the Company recognized $1.6 million in collaboration and license revenue previously recorded in deferred revenue.

Multiple element arrangements

Many of the Company’s instrument sales involve the delivery of multiple products and services. The elements of an instrument sale typically include the instrument installation (when required), an implied one year service type warranty, and in some cases the Company may also sell assays, consumables, or other services. Revenue recognition for contracts with multiple deliverables is based on the individual units of accounting determined to exist in the contract. A delivered item is considered a separate unit of accounting when the delivered item has value to the customer on a stand-alone basis. Items are considered to have stand-alone value when they are sold separately by any vendor or when the customer could resell the item on a stand-alone basis.

The consideration received is allocated among the separate units of accounting using the relative selling price method, and the applicable revenue recognition criteria are applied to each of the separate units. The Company determines the estimated selling price for deliverables within the arrangement using vendor-specific objective evidence (VSOE) of selling price, if available. If VSOE is not available, the Company considers if third-party evidence is available. If third-party evidence of selling price or VSOE is not available, the Company uses its best estimate of selling price for the deliverable.

In order to establish VSOE of selling price, the Company must regularly sell the product or service on a standalone basis with a substantial majority priced within a relatively narrow range. If there are not a sufficient number of standalone sales such that VSOE of selling price cannot be determined, then the Company considers whether third party evidence can be used to establish selling price. Due to the lack of similar products and services sold by other companies within the industry, the Company has not established selling price using third-party evidence.

For product and service sales, the Company determines its best estimate of selling price for instruments, consumables, services and assays using average selling prices over a rolling 12‑month period coupled with an assessment of market conditions, as VSOE and third-party evidence cannot be established. The Company recognizes revenue for delivered elements only when it determines there are no uncertainties regarding customer acceptance.

Distributor transactions

In certain markets, the Company sells products and provides services to customers through distributors that specialize in life sciences products. In cases where the product is delivered to a distributor, revenue recognition generally occurs when title transfers to the distributor. The terms of sales transactions through distributors are generally consistent with the terms of direct sales to customers, except the distributors do not require the Company’s services to install the instrument at the end customer and perform the services for the customer that are beyond our standard warranty in the first year following the sale. These transactions are accounted for in accordance with the Company’s revenue recognition policy described herein.

Business combinations

Amounts paid for acquisitions are allocated to the assets acquired and liabilities assumed, if any, based on their fair values at the dates of acquisition. The fair value of identifiable intangible assets is based on detailed valuations that use information and assumptions determined by management. Any excess of purchase price over the fair value of the net tangible and intangible assets acquired is allocated to goodwill.

The Company typically uses the discounted cash flow method to value acquired intangible assets. This method requires significant management judgment to forecast future operating results and establish residual growth rates and discount factors. The estimates used to value and amortize intangible assets are consistent with the plans and estimates that are used to manage the business and are based on available historical information. If the subsequent actual results and updated projections of the underlying business activity change compared with the assumptions and projections used to develop these values, the Company could experience impairment charges. In addition, the Company has estimated the economic lives of certain acquired assets and these lives are used to calculate depreciation and amortization expense. If estimates of the economic lives change, depreciation or amortization expenses could be accelerated or slowed.

Restricted Cash

Restricted cash represents collateral for a letter of credit issued as security for the lease for the Company’s new headquarters. The restricted cash is long term in nature as the Company will not have access to the funds until more than one year from December 31, 2018.

Cost of revenue

Cost of product revenue consists of raw materials, parts costs and associated freight, shipping and handling costs, contract manufacturer costs, personnel costs, yield loss, in-license payments and royalties, stock-based compensation, other direct costs and overhead.

Cost of service and other revenue consists of personnel, facility costs associated with operating the Accelerator Labs on behalf of the customers, costs related to instrument maintenance and servicing equipment at customer sites, other direct and overhead.

Cost of license revenue, related party consists of license fees that are the direct results of cash payments received related to license agreements.

Research and development expenses

Research and development expenses, including personnel costs, allocated facility costs, lab supplies, outside services, contract laboratory cost are charged to research and development expense as incurred. The Company accounts for nonrefundable advance payments for goods and services that will be used in future research and development activities as expense when the service has been performed or when the goods have been received.

Selling, general, and administrative expense

Selling, general, and administrative expenses are primarily composed of compensation and benefits associated with sales and marketing, finance, human resources, and other administrative personnel, outside marketing, advertising, allocated facilities costs, legal expenses, and other general and administrative costs.

Net loss per share

Basic net loss per common share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares. For purposes of the diluted net loss per share calculations, preferred stock, unvested restricted common stock, and common stock options are considered to be potentially dilutive securities, but are excluded from the diluted net loss per share because their effect would be anti-dilutive and therefore basic and diluted net loss per share were the same for all periods presented.

The following table set forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares):


	Year Ended December 31,
	2018	2017	2016
Series A redeemable convertible preferred stock	—	—	4,884,869
Series B redeemable convertible preferred stock	—	—	1,873,561
Series C redeemable convertible preferred stock	—	—	2,677,649
Series D redeemable convertible preferred stock	—	—	3,864,421
Unvested restricted common stock	361,468	177,192	376,248
Outstanding stock options	2,476,911	2,249,843	1,119,671
Outstanding preferred warrants	—	—	326,374
Outstanding common stock warrants	76,041	86,090	—
Total	2,914,420	2,513,125	15,122,793

As of December 31, 2018, 2017, and 2016 the Company had an obligation to issue warrants to purchase an additional 93,341 shares of common stock, 300,000 shares of Series A‑3 Preferred Stock, and 300,000 shares of Series A‑3 Preferred Stock, respectively, to a vendor if a contract is terminated prior to a minimum purchase commitment being met. Upon completion of the IPO in December 2017, the warrants to purchase shares of Preferred Stock were converted to warrants to purchase shares of common stock at a one-for‑3.214 basis. No amounts are presented in the table above for this obligation to issue a warrant as the issuance of the warrant is not considered probable.

The Company’s redeemable convertible preferred stock was entitled to receive dividends based on dividends declared to common stockholders, thereby giving the preferred stockholders the right to participate in undistributed earnings of the Company above the stated dividend rate. However, preferred stockholders did not have a contractual obligation to share in the net losses of the Company. The Company operated in a net loss position for the years ended December 31, 2018, 2017, and 2016 and, therefore the Company’s accounting for basic and diluted earnings per share was unaffected by the participation rights of the preferred stockholders.

Cash and Cash equivalents

Cash and Cash equivalents consists of cash deposits and short-term, highly liquid investments that are readily convertible into cash, with original maturities of three months or less. Cash equivalents are carried at fair value based on quoted prices for identical assets. Cash and cash equivalents consists of the following (in thousands):


	Year Ended December 31,
	2018		2017
Cash and Cash Equivalents
Cash	$	1,821	$	1,500
Money Market funds invested in U.S. Treasury obligations		42,608		78,182
Total cash and cash equivalents	$	44,429	$	79,682

Restricted cash and deposits

As of December 31, 2018 and 2017, the Company had $1.4 million and $0.4 million, respectively, in restricted cash and deposits related to amounts held for a line of credit, amounts held as a security deposit for the Company’s facility lease obligation, and a business registration application. $1.0 million of the $1.4 million is recorded on a separate line item as restricted cash. The remaining $0.4 million is included in current and noncurrent assets.

Accounts Receivable and allowance for doubtful accounts

The Company provides credit, in the normal course of business, to customers and does not require collateral. Accounts receivable consist of amounts due to the Company for sales to customers and are recorded net of an allowance for doubtful accounts. The Company reviews accounts receivable on a regular basis to determine if any receivable will potentially be uncollectable and to estimate the amount of allowance for doubtful accounts necessary. Once a receivable is deemed uncollectible, such balance is written off and charged against the allowance for doubtful accounts. The Company has not incurred material write offs in any of the periods presented.

Inventory

Inventory is stated at the lower of cost or market on a first-in, first-out (FIFO) basis. The Company analyzes its inventory levels on each reporting date and writes down inventory that is expected to expire prior to being sold and inventory in excess of expected sales requirements. In the event that the Company identifies these conditions exist in its inventory, the carrying value is reduced to its estimated net realizable value.

Property and equipment

Property and equipment, including leasehold improvements, are stated at cost and are depreciated, or amortized in the case of leasehold improvements, over their estimated useful lives using the straight-line method. Expenditures for maintenance and repairs are charged to expense as incurred, whereas major betterments are capitalized as additions to property and equipment. The Company reviews its property and equipment whenever events or changes in circumstances indicate that the carrying value of certain assets might not be recoverable and recognizes an impairment loss when it is probable that an asset’s realizable value is less than the carrying value. To date, no such impairment losses have been recorded. Depreciation is calculated based upon the following estimated useful lives of the assets:


Laboratory and manufacturing equipment		Five years
Computers and software		Three years
Office furniture and equipment		Seven years
Leasehold improvements		Shorter of the useful life of the asset or the remaining term of the lease

Software development costs

The Company develops and modifies software related to the operation of the instrument. Software development costs are expensed as incurred until the point the Company establishes technological feasibility. Based on the Company’s product development process, technological feasibility is established upon the completion of a working model. The Company does not incur material costs between the completion of the working model and the point at which the product is ready for release. Therefore, software development costs are charged to the statement of operations as incurred as research and development expense.

Investments

During the third quarter of 2016, the Company purchased a minority interest in preferred stock in a privately held company for $0.3 million. In addition, in the third quarter of 2018, the Company executed a convertible note with a privately held company for $0.2 million. The investments are recorded on a cost basis in other non-current assets on the accompanying consolidated balance sheets as the Company does not have a controlling investment, does not have the ability to exercise significant influence over the privately held company and the fair value of these equity investments are not readily determinable. The Company performs an impairment analysis at each reporting period to determine if the carrying value of the investment or the note must be reduced due to a decrease in the value of the investment, which includes consideration of whether an event or change in circumstances has occurred that may have a significant adverse effect on the fair value of the investment. The Company determined there was no impairment during the years ended December 31, 2018, 2017, and 2016.

Fair value of financial instruments

ASC Topic 820, Fair Value Measurement (ASC 820), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances.

ASC 820 identifies fair value as the exchange price, or exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following:

Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities.

Level 2 inputs are inputs other than quoted prices that are observable for the asset or liability, either directly or indirectly; and

Level 3 inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability.

To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

The carrying amount reflected on the balance sheets for cash and cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities approximated their fair values, due to the short-term nature of these instruments. The carrying value of the long-term debt approximates its fair value as the debt arrangement is based on interest rates the Company believes it could obtain for borrowings with similar terms. The Company has an investment in the preferred stock of a privately held company which is recorded within other non-current assets on a cost basis. This cost method investment’s fair value has not been estimated as there are no identified events or changes in circumstances that would indicate a significant adverse effect on the fair value of the investment and to do so would be impractical.

Fair value measurements as of December 31, 2018 are as follows (in thousands):


			Quoted		Significant
			prices		other		Significant
			in active		observable		unobservable
			markets		inputs		inputs
Description	Total		(Level 1)		(Level 2)		(Level 3)

Financial Assets
Cash Equivalents	$	42,608	$	42,608		—	$	—
Note receivable		150		—		—		150
Total	$	42,758	$	42,608		—	$	150

Fair value measurements as of December 31, 2017 are as follows (in thousands):

Quoted

Significant

prices

other

Significant

in active

observable

unobservable

markets

inputs

Description

Total

(Level 1)

(Level 2)

(Level 3)

Financial Assets

Cash Equivalents

78,182

—

Total

78,182

—

As of January 1, 2016, the Company had outstanding warrants to purchase 64,441 shares of Series A‑2 redeemable convertible preferred stock (Series A‑2 Preferred Stock), 1,300,000 shares of Series A‑3 convertible preferred stock (Series A‑3 Preferred Stock), 562,488 shares of Series B redeemable convertible preferred stock (Series B Preferred Stock), and 226,733 shares of Series C redeemable convertible preferred stock (Series C Preferred Stock). During the years ended December 31, 2017, and 2016, the Company issued the following warrants:

On January 29, 2016, the Company issued a warrant to purchase 57,810 shares of Series C Preferred Stock to a lender related to a second amendment to a debt facility (Note 8)

On November 18, 2016, the Company issued a warrant to purchase 700,000 shares of Series A‑3 Preferred Stock to a vendor (Note 7).

On March 31, 2017, the Company issued a warrant to purchase 38,828 shares of Series D redeemable convertible preferred stock (Series D Preferred Stock) to a lender as part of a third amendment to a debt facility (Note 8).

All of the warrants were initially recorded as a preferred stock warrant liability on the accompanying consolidated balance sheets at fair value. Warrants issued for goods or services are initially accounted for under ASC 505‑50 and are recognized over the required performance period in the consolidated statements of operations or consolidated balance sheets at the vesting date or reporting date fair value based on the nature of the underlying arrangement. Warrants issued in connection with a product development contract were recorded to research and development expense. Warrants issued in connection with a revenue arrangement were recorded as a reduction in revenue. Warrants issued in connection with debt arrangements were recorded as a reduction in the carrying value of debt. They are marked to market on each reporting and exercise date with changes in the fair value recorded in other expense (income) on the statement of operations and comprehensive loss. Holders of warrants to purchase 700,000 shares of Series A‑3 Preferred stock, and holders of warrants to purchase 111,114 shares of Series C Preferred Stock exercised the warrants during the year ended December 31, 2017. Upon exercise, the fair value of the warrants was reclassified to redeemable convertible preferred stock along with any proceeds received. Upon completion of the IPO, the outstanding warrants to purchase shares of preferred stock were automatically converted into warrants to purchase shares of common stock and are therefore accounted for as equity instruments.

The changes in preferred stock warrant liability measured at fair value for which the Company has used Level 3 inputs to determine fair value are as follows (in thousands):


	Warrant
	liability
Balance at December 31, 2015	$	5,547
Issuance of warrants related to debt facility		128
Issuance of warrants related to a vendor		2,078
Changes in fair value of warrants		307
Warrant exercises		(5,258)
Balance at December 31, 2016		2,802
Issuance of warrants related to debt facility		119
Changes in fair value of warrants		90
Warrant exercises		(2,188)
Conversion to warrants to purchase common stock in connection with IPO		(823)
Balance at December 31, 2017	$	—

Prior to the completion of the IPO, the warrants were classified as liabilities because they were exercisable for shares of redeemable convertible preferred stock. On each measurement date and immediately prior to the IPO and the resulting change in classification of the warrants to equity instruments, the Company utilized a black-scholes option pricing model to determine the fair value of the warrants and utilized various valuation assumptions based on available market data and other relevant but unobservable factors. Expected volatility for the Company’s redeemable convertible preferred stock was determined based on an analysis of the historical volatility of a representative group of guideline public companies because, prior to the IPO, there was no market for the Company’s common stock and, therefore, a lack of market-based company-specific historical and implied volatility information. The expected term reflects the remaining contractual term of the warrants. The assumed dividend yield is based upon the Company’s expectation of not paying dividends in the foreseeable future. The risk-free rate is based upon the U.S. Treasury yield curve in effect at the valuation date, commensurate with the remaining contractual life of the warrants. The fair value of the underlying preferred shares was determined by management, with the assistance of a third party valuation specialist, using a hybrid valuation method, which includes a probability weighted analysis of two scenarios. The first scenario was based on the completion of an initial public offering utilizing a market approach and the second scenario was based on the Company remaining privately held utilizing either an income approach or a weighted-average of an income approach and a backsolve to a recent financing event, depending on the proximity of the financing event to the measurement date. The assumption regarding the Company’s probability of completing an initial public offering was the primary contributing factor to the changes in fair value of the underlying preferred stock. See "Stock-based Compensation" section of this “Significant Accounting Policies” (Note 2) for discussion of the changes of the probability of completing an initial public offering.

The following assumptions were utilized to determine the fair value of each warrant to purchase preferred stock at each reporting period and as of the change from liability to equity accounting treatment of the warrants in connection with the IPO:

Value of

underlying

Probability

Series D

Series C

Series B

Series A‑3

Series A‑2

of an initial

preferred

public

Balance sheet date

stock

Volatility

offering

December 7, 2017

4.67

N/A

4.67

100

Warranties

The Company provides a one-year warranty and maintenance service related to its instruments and sells extended warranty contracts for additional periods. The Company defers revenue associated with these services and recognizes them on a pro-rata basis over the period of service.

Income taxes

The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s consolidated financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the consolidated financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740 Income Taxes (ASC 740). When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. As of December 31, 2018 and 2017 the Company did not have any significant uncertain tax positions.

Credit, product and supplier concentrations and off-balance-sheet risk

The Company has no significant off-balance-sheet risk, such as foreign exchange contracts, option contracts, or other hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk primarily consist of cash and cash equivalents and a cost method investment. The Company places its cash and cash equivalents principally in depository accounts with a bank.

The Company is also subject to supply chain risks related to the outsourcing of the manufacturing of its instruments. Although there are a limited number of manufacturers for instruments of this type, the Company believes that other suppliers could provide similar products on comparable terms. A change in suppliers, however, could cause a delay in manufacturing and a possible loss of sales, which would adversely affect operating results. In addition to outsourcing the manufacturing of its instruments, the Company also purchases antibodies through a number of different suppliers. Although a disruption in service from any one of its antibody suppliers is possible, the Company believes that it would be able to find an adequate supply from alternative suppliers.

Customers outside the United States represented 40% and 34% of the Company’s gross trade accounts receivable balance as of December 31, 2018 and 2017 respectively.

At December 31, 2018, no single customer represented 10% of the Company’s aggregate accounts receivable, and no single customer represented 10% of the Company’s revenue for the year ended December 31, 2018. At December 31, 2017, one customer’s accounts receivable balance was 16% of the Company’s aggregate accounts receivable no single customer represented 10% of the Company’s revenue for the year ended December 31, 2017. At December 31, 2016, one customer’s account receivable balance was 26% of the Company’s aggregate accounts receivable and represented 11% of the Company’s revenue for the year ended December 31, 2016.

Segment information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company and the Company’s chief operating decision-maker reviews the Company’s operations and manages its business as a single operating segment.

Net revenue by product and service line are as follows (in thousands):


	Year ended December 31,
	2018		2017		2016
Product revenue	$	23,365	$	14,124	$	10,601
Service and other revenue		12,117		7,676		5,012
Collaboration and license revenue		2,150		1,074		1,972
Total revenue	$	37,632	$	22,874	$	17,585

The following table reflects total revenue (in thousands) by geography and as a percentage of total revenue, based on the billing address of our customers. North America consists of the United States, Canada and Mexico; EMEA consists of Europe, Middle East, and Africa; and Asia Pacific includes Japan, China, South Korea, Singapore, Malaysia and Australia.


	Year ended December 31,
	2018				2017				2016
North America	$	22,706	60	%	$	13,864	61	%	$	13,018	74	%
EMEA		11,742	31	%		6,922	30	%		3,416	19	%
Asia Pacific		3,184	8	%		2,088	9	%		1,151	7	%
Total	$	37,632	100	%	$	22,874	100	%	$	17,585	100	%

Stock-based compensation

The Company accounts for stock-based compensation awards in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 718, Compensation—Stock Compensation (ASC 718). ASC 718 requires all stock-based payments to employees, including grants of employee stock options, to be recognized in the statement of operations based on their fair values. Stock-based compensation awards have historically consisted of stock options and restricted stock.

Prior to adoption of ASU 2016‑09 on January 1, 2017, the Company recognized compensation costs related to stock options granted to employees based on the estimated fair value of the awards on the date of grant, net of estimated forfeitures. Effective January 1, 2017, the Company ceased utilizing an estimated forfeiture rate and began recognizing forfeitures as they occur. The Company estimates the grant date fair value, and the resulting stock-based compensation expense, using the Black-Scholes option-pricing model. The grant date fair value of the stock-based awards is generally recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the respective awards.

The Company recognizes compensation costs related to share-based payments granted to non-employees based on the estimated fair value of the awards on the date of grant in the same manner as options for employees; however, the fair value of the stock options granted to non-employees is re-measured each reporting period until the service is complete, and the resulting increase or decrease in value, if any, is recognized as expense or income, respectively, during the period the related services are rendered to the same financial statement line item as any cash consideration would be recognized. There were no material non-employee awards outstanding during the years ended December 31, 2018, 2017, and 2016.

The fair value of stock options granted to employees and directors for their services on the Company’s Board of Directors is estimated on the grant date using the Black-Scholes option-pricing model, based on the assumptions noted in the following table:


	Year Ended December 31,
	2018		2017		2016
Risk-free interest rate	2.6% - 3.0	%	1.8% - 2.1	%	1.2% - 1.3	%
Expected dividend yield	None		None		None
Expected term (in years)	5.9		6.0		6.0
Expected volatility	32.4% - 36.8	%	46.0% - 52.0	%	44.9% - 49.0	%

Using the Black-Scholes option-pricing model, the weighted-average grant date fair value of options granted for the years ended December 31, 2018, 2017, and 2016 was $7.19, $4.52, and $2.41 per share, respectively. Expected volatility was calculated based on reported volatility data for a representative group of guideline publicly traded companies for which historical information was available. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant, commensurate with the expected life assumption. The Company estimates the expected life of options granted to employees utilizing the simplified method which calculates the expected life of an option as the average of the time to vesting and contractual life of the options. The expected life is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its employee population. The Company uses the simplified method due to the lack of historical exercise data and the plain nature of the stock options. The Company uses the remaining contractual term for the expected life of non-employee awards. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on common stock. Prior to the completion of the IPO, the fair value of the underlying common shares was determined by management, with the assistance of a third party valuation specialist, using a hybrid valuation method, which includes a weighted analysis of two scenarios. The first scenario is based on the completion of an initial public offering utilizing a market approach and the second scenario is based on the Company remaining privately held utilizing either an income approach or a weighted-average of an income approach and a backsolve to a recent financing event approach, depending on the proximity of the financing event to the measurement date. The initial public offering scenario reflected data gathered from relevant comparable initial public offering transactions and the current value method of equity allocation was used in determining the value of common stock. For the privately held scenario, traditional income methods of business valuation were employed, where the total equity value was then allocated using the option pricing model (OPM). The assumption regarding the Company’s probability of completing an initial public offering was the primary contributing factor to the changes in fair value of the common stock. The probability of initial public offering was 40% at December 31, 2016. Since December 31, 2015, the Company had performed the common stock valuations on a quarterly basis. Upon completion of the IPO in December 2017, the Company determines the fair value of the underlying common shares based on the closing price of the common stock on the option grant date.

The probability of completing an initial public offering was based on the facts and circumstances as of each measurement date. During the three months ended December 31, 2016, the Company began initial preparations for completing an initial public offering; including assessing quarterly financial information and holding initial discussions with prospective investment bankers, which resulted in an increase in the probability of completing an initial public offering. Subsequent to March 31, 2017, the Company obtained approval from the Board of Directors to pursue the transaction, selected investment bankers, held an organizational meeting, and performed other procedures necessary to complete an initial public offering. As a result, the probability of completing an initial public offering increased subsequent to March 31, 2017.

The Company is using the straight-line attribution method to recognize stock-based compensation expense for service based awards for employees and non-employees. However, cumulative compensation expense recognized through the end of any period must at least equal the value of vested awards through that period, with compensation expense adjusted accordingly. For the year ended December 31, 2016, the amount of stock-based compensation expense recognized during a period was based on the value of the portion of the awards that were ultimately expected to vest. Prior to January 1, 2017, forfeitures were estimated at the time of grant, and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. During the year ended December 31, 2016, the Company applied an estimate of forfeitures which did not have a material effect on the consolidated financial statements. Effective January 1, 2017, the Company adopted Accounting Standards Update (ASU) 2016‑09 Stock Compensation, and has elected to account for forfeitures as incurred and therefore no forfeiture estimate is utilized in the years ended December 31, 2018 and 2017. The effect of this adoption has been recorded as a $0.1 million cumulative effect adjustment to accumulated deficit as of January 1, 2017.

The Company applies an accelerated attribution method to recognize stock-based compensation expense when accounting for performance-based stock awards. The Company records the expense for stock-based compensation awards subject to performance-based milestone vesting over the remaining service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the expected satisfaction of the performance conditions as of the reporting date. Compensation expense for performance-based stock awards is included in total stock-based compensation expense. There were no material performance-based stock awards outstanding as of December 31, 2018, 2017, and 2016.

Recent accounting pronouncements

The Company is considered to be an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012, as amended (JOBS Act). The JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. Thus, an emerging growth company can delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. The Company has elected to avail itself of this extended transition period and, as a result, the Company will not be required to adopt new or revised accounting standards on the relevant dates on which adoption of such standards is required for other public companies so long as the Company remains an emerging growth company.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (ASC 606). The FASB has issued several updates to the standard which clarify the (i) application of the principal versus agent guidance; (ii) guidance relating to performance obligations and licensing; (iii) assessment of the collectability criterion, presentation of sales taxes, measurement date for non-cash consideration and completed contracts at transition; and (iv) narrows aspects of ASC 606 or corrects unintended application of the guidance (collectively, the Revenue ASUs). The Revenue ASUs provide an accounting standard for a single comprehensive model for recognizing revenue arising from contracts with customers. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. In conjunction with the new revenue standard, the FASB also amended the guidance under ASC 340-40, Other Assets and Deferred Costs – Contracts with Customers, related to the accounting for costs to obtain or fulfill a contract with a customer. The Company will adopt the new revenue standard as of January 1, 2019 using the modified retrospective method. The Company is still in the process of quantifying the impact of the standard.

In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). The standard changes how entities measure certain equity investments and present changes in the fair value of financial liabilities measured under the fair value option that are attributable to their own credit. Under the new guidance, entities will be required to measure equity investments that do not result in consolidation and are not accounted for under the equity method at fair value and recognize any changes in fair value in net income unless the investments qualify for the new practicability exception. The Company’s assessment is in progress and has not yet concluded on the impact of the standard.

In February 2016, the FASB established Topic 842, Leases, by issuing ASU No. 2016-02, which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use model (“ROU”) that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. The new standard is effective for us on January 1, 2020, with early adoption permitted. We expect to adopt the new standard on January 1, 2020 and use the effective date as our date of initial application.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, to address diversity in how certain cash receipts and cash payments are presented and classified in the statements of cash flows. The amendments are effective for the Company for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The amendments should be applied using a retrospective transition method to each period presented. If retrospective application is impractical for some of the issues addressed by the update, the amendments for those issues would be applied prospectively as of the earliest date practicable. As the Company avails itself to the extended transition period as an emerging growth company under the JOBS Act, the new standard is effective for fiscal years beginning after December 15, 2018 and interim periods within fiscal years beginning after December 15, 2019. The Company’s assessment is in progress and has not yet concluded on the impact of the standard.

In November 2016, the FASB issued ASU No. 2016‑18, Statement of Cash Flows (Topic 230): Restricted Cash (ASU 2016‑18), requiring restricted cash and cash equivalents to be included in the statement of cash flows. As the Company avails itself of the extended transition period as an emerging growth company under the JOBS Act, the new standard is effective for fiscal years beginning after December 15, 2018 and interim periods within fiscal years beginning after December 15, 2019. The Company elected to early adopt this standard in the statement of cash flows for the year ended December 31, 2018.

In January 2017, the FASB issued ASU No. 2017‑04 Intangibles - Goodwill and Other (Topic 350) - Simplifying the Test for Goodwill Impairment. This ASU eliminates Step 2 from the goodwill impairment test. In addition, income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit should be considered when measuring the goodwill impairment loss, if applicable. The amendments also eliminate the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. This ASU is effective for annual periods beginning after December 15, 2019 and interim periods within those annual periods. Early adoption is permitted, for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company does not expect adoption of this ASU to be material to its financial statements on known trends, demands, uncertainties and events in its business.

In August 2018, the FASB issued ASU No. 2018‑13, “Fair Value Measurement (Topic 820), Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement”. This ASU removed the following disclosure requirements: (1) the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy; (2) the policy for timing of transfers between levels; and (3) the valuation processes for Level 3 fair value measurements. Additionally, this update added the following disclosure requirements: (1) the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period; (2) the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. For certain unobservable inputs, an entity may disclose other quantitative information (such as the median or arithmetic average) in lieu of the weighted average if the entity determines that other quantitative information would be a more reasonable and rational method to reflect the distribution of unobservable inputs used to develop Level 3 fair value measurements. ASU No. 2018‑13 will be effective for fiscal years beginning after December 15, 2019 with early adoption permitted. As of December 31, 2018, the Company has not elected to early adopt this guidance but does not expect that the adoption of this guidance will have a material effect on its consolidated financial statements.

Inventory

12 Months Ended

Dec. 31, 2018

Inventory

Inventory

3. Inventory

Inventory consists of the following (in thousands):


	As of
	December 31,
	2018		2017
Raw materials	$	1,546	$	1,032
Work in process		2,331		968
Finished goods		2,068		1,571
Total	$	5,945	$	3,571

Inventory comprises commercial instruments, assays, and the materials required to manufacture assays.

Property and equipment

12 Months Ended

Dec. 31, 2018

Property and equipment

Property and equipment

4. Property and equipment

Property and equipment consists of the following (in thousands):


	As of
	December 31,
	2018		2017
Laboratory and manufacturing equipment	$	4,127	$	2,969
Office furniture and equipment		789		689
Computers and software		786		459
Leasehold improvements		244		180
		5,946		4,297
Less: accumulated depreciation		(3,023)		(2,423)
Total	$	2,923	$	1,874

The Company incurred depreciation expense of $0.7 million, and $0.5 million for the years ended December 31, 2018 and 2017, respectively. Included in Laboratory and manufacturing equipment are 27 instruments, which are internally used by the Company. The laboratory & manufacturing equipment balance includes $1.4 million of cost and $0.7 million of accumulated depreciation related to these instruments.

Other accrued expenses

12 Months Ended

Dec. 31, 2018

Other accrued expenses

Other accrued expenses

5. Other accrued expenses

Other accrued expenses consist of the following (in thousands):


	As of December 31,
	2018		2017
Accrued inventory	$	599	$	835
Accrued royalties		323		221
Accrued professional services		723		346
Accrued development costs		795		1,559
Accrued other		689		599
Total accrued expenses	$	3,129	$	3,560

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Taxes

Income Taxes

6. Income Taxes

The following table presents the components of income (loss) before income taxes (in thousands):


	Year Ended December 31,
	2018		2017		2016
United States	$	(31,436)	$	(27,019)	$	(23,173)
Foreign		(75)		—		—
	$	(31,511)	$	(27,019)	$	(23,173)

The following table summarizes the provision for (benefit from) income taxes (in thousands):


	Year Ended December 31,
	2018		2017		2016
Current:
United States
Federal	$	—	$	—	$	—
State		18		—		—
Foreign		—		—		—
Total current income tax provision		18		—		—
Deferred
United States
Federal		2		—		—
State		5		—		—
Foreign		—		—		—
Total deferred income tax provision (benefit)		7		—		—
Total income tax provision (benefit)	$	25	$	—	$	—

During the years ended December 31, 2018 and 2017, the Company recorded an income tax provision of $25 and $0 thousand, respectively. During the years ended December 31, 2018, 2017 and 2016, the Company recorded no income tax benefits for any net losses incurred and the tax credits generated in each year, due to its uncertainty of realizing a benefit from those items.

A reconciliation of the federal statutory income tax rate to the effective tax rate is as follows:


	Year Ended December 31,
	2018		2017
Federal statutory income tax rate	21.0	%	34.0	%
State taxes, net of federal tax benefit	6.0	%	4.8	%
Stock compensation	1.1	%	0.0	%
Permanent items	(1.2)	%	(1.6)	%
Tax Credits	2.7	%	2.6	%
Foreign differential	0.0	%	0.0	%
U.S. Tax Reform	0.0	%	(53.2)	%
Other, net	0.2	%	(1.1)	%
Valuation Allowance	(29.9)	%	14.5	%
Effective income tax rate	(0.1)	%	0.0	%

The significant reconciling items between the reported amounts of income tax expense for the year to the amount of income tax expense that would result from applying the U.S. statutory tax rate to pre-tax income include state taxes, non-deductible expenses, stock based compensation tax benefits, tax credits, and the valuation allowance maintained against certain of the Company’s deferred tax assets.

During 2018, the Company acquired Aushon Biosystems. The Company analyzed the transaction from an income tax perspective and adjusted the deferred tax assets and liabilities related to the Aushon Biosystems acquisition. Of the total goodwill recorded, approximately $0.4 million is amortizable related to historical tax basis that Aushon had related to a prior acquisition.

On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the “Act”) was signed into law, making significant changes to the Internal Revenue Code. Changes included, but were not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S international taxation from a worldwide tax system to a territorial system, and a one-time transition tax on the mandatory deemed repatriation of cumulative deferred foreign earnings as of December 31, 2017. On December 22, 2017, Staff Accounting Bulletin No. 118 (“SAB 118”) was issued, which directed taxpayers to consider the impact of the Act as “provisional” when a registrant did not have the necessary information available, prepared or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act. During the fourth quarter of 2018 the Company completed its accounting for the tax effects of the Act and recorded no adjustments in its consolidated financial statements.

A valuation allowance is provided when it is more likely than not that all or a portion of the deferred tax asset will not be realized. Realization of deferred tax assets is dependent upon future taxable income, if any, the amount and timing of which are uncertain. The Company maintains a valuation allowance against its net U.S. and foreign deferred tax assets as a result of the negative evidence associated with its history of operating losses.

Deferred tax assets and liabilities reflect the net tax effects of net operating loss carryovers and temporary differences between the carrying amount of assets and liabilities for financial reporting and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities were as follows (in thousands):


	December 31,
	2018		2017
Deferred tax assets:
Net operating loss carryforwards	$	35,623	$	27,952
Research and development credits		4,678		3,637
Deferred revenue		1,614		1,795
Depreciation		86		629
Amortization		792		—
Stock compensation		541		185
Other deferred tax assets		1,378		614
Total deferred tax assets		44,712		34,812
Valuation allowance		(44,033)		(34,552)
Subtotal		679		260
Section 481(a) Adjustment - Accrued Bonus		(59)		(118)
Amortization		(610)		—
Goodwill		(17)
Stock-based compensation		—		(142)
Net deferred tax assets (liability)	$	(7)	$	—

As of December 31, 2018, the Company had federal and state net operating loss carryforwards of $136.8 million and $108.8 million, respectively. $0.9 million of the federal net operating loss carryforwards relates to the acquisition of Aushon Biosystems and these losses have been reduced to reflect the limitations on these losses as a result of Section 382 of the Internal Revenue Code. These carryforwards begin to expire in 2026 and 2019, respectively. As of December 31, 2018, the Company had federal and state credit carryforwards of $3.8 million and $1.2 million, respectively. These carryforwards begin to expire in 2026 and 2019, respectively. As of December 31, 2018, the Company had foreign net operating loss carryforwards of $75 thousand. Of this amount, carryforwards of $75 thousand expire in 2027.

The Company recognizes a deferred tax asset for the future benefit of tax loss carryforwards, tax credit carryforwards, and other deductible temporary differences to the extent that it is more likely than not that these assets will be realized. In evaluating the Company’s ability to recover these deferred tax assets, the Company considers all available positive and negative evidence, including its past operating results, taxable income in carryback years, the projected reversal of existing deferred tax liabilities, the availability of tax planning strategies and its forecast of future taxable income. Based on the significant negative evidence, including the three-year cumulative loss position, the Company concluded that its net U.S. deferred tax assets as well as the deferred tax assets in certain foreign subsidiaries were not more likely than not realizable and maintained a full valuation allowance against these deferred tax assets at December 31, 2018.

The valuation allowance increased by $9.4 million during the year ended December 31, 2018, primarily as a result of the U.S. operating losses incurred, the research and development tax credit carryforwards generated during the year and acquisition of Aushon Biosystems, Incorporated.

The valuation allowance decreased by $3.9 million during the year ended December 31, 2017. The decrease in valuation allowance was primarily the result of the impact of the U.S. corporate tax rate reduction enacted during 2017, which resulted in the Company remeasuring its deferred tax assets and liabilities at the lower 21% U.S. federal corporate tax rate and a corresponding reduction in the valuation allowance. This reduction was partially offset by the valuation allowance established in 2017 related to U.S. and foreign operating losses incurred and tax credits generated during the year.

Under Sections 382 and 383 of the U.S. Internal Revenue Code, if a corporation undergoes an ownership change, the corporation’s ability to use its pre-change net operating loss carryforwards and other pre-change tax attributes, such as research tax credits, to offset its post-change income and taxes may be limited. In general, an ownership change generally occurs if there is a cumulative change in its ownership by 5% stockholders that exceeds 50 percentage points over a rolling three-year period. Similar rules may apply under U.S. state tax laws. The Company may have experienced an ownership change in the past and may experience ownership changes in the future as a result of future transactions in its share capital, some of which may be outside of the control of the Company. As a result, if the Company earns net taxable income, its ability to use its pre-change net operating loss carryforwards, or other pre-change tax attributes, to offset U.S. federal and state taxable income and taxes may be subject to significant limitations.

In the ordinary course of business, there is inherent uncertainty in quantifying the Company’s income tax positions. The Company assesses income tax positions and records tax benefits for all years subject to examination based upon management’s evaluation of the facts, circumstances, and information available at the reporting date. For those tax positions for which it is more likely than not that a tax benefit will be sustained, the Company recorded the largest amount of tax benefit with a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority that has full knowledge of all relevant information. For those income tax positions for which it is not more likely than not that a tax benefit will be sustained, no tax benefit has been recognized in the consolidated financial statements.

The Company accounted for uncertain tax positions using a more likely than not threshold for recognizing and resolving uncertain tax positions. The evaluation of uncertain tax positions is based on factors that include, but are not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity and changes in facts or circumstances related to a tax position. The Company evaluates uncertain tax positions on an annual basis and adjusts the level of the liability to reflect any subsequent changes in the relevant facts surrounding the uncertain positions. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes. For the years ended December 31, 2018, 2017 and 2016, there were no accrued interest or penalties in the consolidated statements of operations and comprehensive loss. The Company does not anticipate any significant changes in the next twelve months associated with its liability for unrecognized tax benefits.

The Company is subject to taxation in the United States as well as the Netherlands and China. At December 31, 2018, the Company is generally no longer subject to examination by taxing authorities in the United States for years prior to 2015. However, net operating loss carryforwards and credits in the United States may be subject to adjustments by taxing authorities in future years in which they are utilized. The Company’s foreign subsidiaries remain open to examination by taxing authorities from 2018 onward.

The Company’s foreign subsidiary has incurred losses since inception, and the Company had immaterial undistributed earnings as of December 31, 2018.

Redeemable convertible preferred stock

12 Months Ended

Dec. 31, 2018

Redeemable convertible preferred stock

Redeemable convertible preferred stock

7. Redeemable convertible preferred stock

The Company had authorized 47,015,449 shares of preferred stock, $0.001 par value per share, of which 3,972,415 shares were designated Series A‑1 redeemable convertible preferred stock (Series A‑1 Preferred Stock), 10,492,027 shares were designated Series A‑2 Preferred Stock, 2,000,000 shares were designated Series A‑3 Preferred Stock, 6,186,594 shares were designated Series B Preferred Stock, 9,247,089 shares were designated as Series C Preferred Stock, 544,332 shares were designated Series C‑1 redeemable convertible preferred stock (Series C‑1 Preferred Stock), 12,459,090 shares were designated Series D Preferred Stock and 2,113,902 were designated Series D‑1 redeemable convertible preferred stock (Series D‑1 Preferred Stock) as of immediately prior to the completion of the IPO.

In February 2016, the Company issued 1,300,000 shares of Series A‑3 Preferred Stock to a vendor (Note 8) upon the exercise of Series A‑3 Preferred Stock warrants at a purchase price of $0.001 per share. The fair value of the settled warrant was $3.9 million at the time of exercise which was reclassified from Preferred Stock Warrant Liability to Series A Preferred Stock.

In March 2016, the Company issued 12,420,262 shares of Series D Preferred Stock at a purchase price of $3.67 per share. The issuance resulted in cash proceeds of $45.4 million, net of issuance costs.

In June and July 2016, the Company issued 397,530 shares of Series B Preferred Stock upon exercise of Series B Preferred Stock warrants, which included 312,500 shares of Series B Preferred Stock at a purchase price of $0.001 per share, 8,330 shares of Series B Preferred Stock at purchase price of $2.00 per share, and 76,700 shares of Series B Preferred Stock upon a cashless exercise of a warrant. The fair value of the settled warrants was $1.4 million at the time of exercise which was reclassified from Preferred Stock Warrant Liability to Series B Preferred Stock.

In January 2017, the Company issued 700,000 shares of Series A‑3 Preferred Stock to a vendor (Note 8) upon the exercise of Series A‑3 Preferred Stock warrants at a purchase price of $0.001 per share. The fair value of the settled warrant was $2.1 million at the time of exercise which was reclassified from Preferred Stock Warrant Liability to Series A Preferred Stock.

In June 2017, the Company issued 2,113,902 shares of Series D‑1 Preferred Stock at a purchase price of $4.021 per share. The issuance resulted in cash proceeds of $8.4 million, net of issuance costs.

In November 2017, the Company issued 31,283 shares of Series C Preferred Stock upon exercise of Series C Preferred Stock warrants, which included 8,474 shares of Series C Preferred Stock at a purchase price of $3.3299 per share, and 22,809 shares of Series C Preferred Stock upon a cashless exercise of a warrant. The fair value of the settled warrants was $0.1 million at the time of exercise which was reclassified from Preferred Stock Warrant Liability to Series C Preferred Stock.

The Company had a Stock Purchase Agreement (SPA) with bioMérieux, a related party, which required the Company to issue additional shares of Series C Preferred Stock if certain milestones were met in exchange for $10.0 million in gross proceeds. The milestones were related to activities under a Joint Development and License Agreement (JDLA) (Note 12). bioMérieux also purchased Series C Preferred Stock when the JDLA was entered into in 2012. When the SPA was entered into, the Company evaluated whether the requirement to issue additional shares (‘Tranche Feature") required separate accounting. The Company determined that the Tranche Feature was not legally detachable and therefore was an embedded feature in the Series C Preferred Stock that bioMérieux purchased.

During the year ended December 31, 2015, the Company amended the terms of the SPA which restructured the equity milestone from one payment of $10.0 million to three separate payments ($5.0 million; $3.0 million and $2.0 million) based on components of the initial technical milestones. No other terms of the Series C Preferred Stock changed. The Company achieved the first milestone in January 2015 at which time bioMérieux purchased 1,501,546 shares of Series C Preferred Stock at a price of $3.3299 for total gross proceeds of $5.0 million. The Company also achieved the second milestone in May 2015 at which time bioMérieux purchased 600,618 shares of Series C Preferred Stock at a price of $3.3299 for total gross proceeds of $2.0 million. In December 2016, the Company further amended the JDLA and SPA which cancelled the third and final milestone (Note 12).

The rights, preferences, and privileges of Series A‑1, A‑2, A‑3, B, C, C‑1, D, and D‑1 Preferred Stock were as follows:

Conversion

Shares of Series A‑1, A‑2, A‑3, B, C, C‑1, D, and D‑1 Preferred Stock were convertible into common stock on a 3.214‑for-one basis, adjustable for certain dilutive events. Conversion was at the option of the preferred stockholders, although conversion was automatic upon the earlier of the consummation of an initial public offering, resulting in gross proceeds to the Company of at least $40.0 million and for a minimum per-share amount of $5.00 per share, or the approval of a Preferred Majority, defined as 60% of the outstanding shares of Series A‑1, A‑2, B, C, D, and D‑1 Preferred Stock voting as a single class.

Dividends

Holders of the Series A‑1, A‑2, B, C, and C‑1 Preferred Stock were entitled to receive, before any cash was paid out or set aside for any common stock, cumulative dividends in arrears at the annual rate of $0.08, $0.08, $0.16, $0.2664, and $0.2664 per share, respectively, subject to adjustment for stock splits, stock dividends, combinations and reorganizations. Holders of Series D, and D‑1 Preferred Stock were entitled to receive non-cumulative dividends at the rate of $0.2936, and $0.3217 per share, respectively, subject to adjustment for stock splits, when and if declared by the Board of Directors of the Company. The cumulative accrued dividends as of immediately prior to the completion of the IPO were $3.3 million, $7.8 million, $5.7 million, $9.5 million, and $0.7 million for Series A‑1, A‑2, B, C and C‑1 Preferred Stock, respectively. Holders of Series A‑3 Preferred Stock were not entitled to receive any preferred stock dividends. Upon full payment of preferred dividends, additional dividends would have been shared among all preferred stock holders and common stock holders on a pro rata basis.

Liquidation preference

Holders of the Series A‑1, A‑2, A‑3, B, C, C‑1, D, and D‑1 Preferred Stock had preference in the event of a liquidation or dissolution of the Company equal to $1.0416667, $1.0416667, $2.00, $2.00, $3.3299, $3.3299, $3.67, and $4.021 per share, respectively, plus any accrued but unpaid dividends. In any liquidation event, Series D and D‑1 Preferred Stock holders would receive first priority in liquidation payments. In the event that the amounts available for distribution were insufficient to pay the full amounts, the assets would be distributed ratably among Series D, and D‑1 Preferred Stock holders in proportion to their aggregate liquidation preference amounts until such amounts were paid full. Series B, C, and C‑1 Preferred Stock holders would receive next priority in liquidation payments after Series D Preferred Stock holders. In the event that the amounts available for distribution were insufficient to pay the full amounts, the assets would be distributed ratably among B, C, and C‑1 Preferred Stock holders in proportion to their aggregate liquidation preference amounts. Series A‑1, A‑2, and A‑3 Preferred Stock holders would receive next priority in liquidation preference after Series B, C, and C‑1 Preferred Stock holders. In the event that the amounts available for distribution after payment were insufficient to pay the full amounts, the assets would be distributed ratably among A‑1, A‑2, and A‑3 Preferred Stock holders in proportion to their aggregate liquidation preference amounts. Any remaining amounts would be distributed to holders of common stock on a pro rata basis. However, if the holders of any series of preferred stock would receive a greater liquidation preference if they were converted into shares of common stock immediately prior to the liquidation event, then these shares would receive consideration equal to the amount that would be received if the shares had been converted in common stock in lieu of the applicable liquidation preference.

Voting rights

Holders of the Series A‑1, A‑2, A‑3, B, C, D and D‑1 Preferred Stock (Voting Preferred) were entitled to vote as a single class with the holders of common stock, and had one vote for each equivalent common share into which the preferred stock was convertible. A Preferred Majority vote was required in order to amend the Certificate of Incorporation or By-Laws, reclassify common stock or establish another class of stock, create or authorize additional shares of preferred stock, effect a sale, liquidation, or merger of the Company, repurchase or redeem any capital stock, or engage in any action which would adversely affect the holders of the preferred stock.

The holders of the Series A‑1, A‑2 and B Preferred Stock could elect three members to the Board of Directors, voting as a single class. The holders of the Series C Preferred Stock could elect one member to the Board of Directors. The holders of the Voting Preferred could elect one member to the Board of Directors, voting as a single class.

Holders of Series C‑1 Preferred Stock had no voting rights.

Prior to the issuance of Series D Preferred Stock in March 2016, a majority vote of the Series B, C and C‑1 Preferred Stock holders could elect to redeem all of the outstanding shares of Series B, C and C‑1 Preferred Stock at any time on or after November 14, 2016. The Series A‑1 and A‑2 Preferred Stockholders had the right to elect to redeem all of the outstanding shares at any time after the redemption of the Series B, C and C‑1 Preferred Stock shares was made. The preferred stockholders were entitled to the redemption in three equal annual installments.

Upon issuance of the Series D Preferred Stock in March 2016, the redemption rights were adjusted. A majority vote of the Series D Preferred Stockholders could elect to redeem all of the outstanding shares of Series D on or after March 18, 2019. Upon issuance of the Series D‑1 Preferred Stock in June 2017 the redemption rights were adjusted. A majority vote of the Series D and D‑1 Preferred Stockholders, voting as separate classes, could elect to redeem all of the outstanding shares of Series D and D‑1 Preferred Stock on or after June 2, 2020. Holders of the Series C‑1, C and B Preferred Stock could only redeem their shares following the redemption in full of all shares of Series D and D‑1 Preferred Stock and upon a Preferred Majority Vote. Holders of the Series A‑1 and A‑2 Preferred Stock could only redeem their shares following the redemption in full of the Series D‑1, D, C‑1, C and B Preferred Stock, and upon a Preferred Majority Vote. Series A‑3 Preferred Stock did not have redemption rights other than in certain deemed liquidation scenarios.

The redemption value of the Series A‑1, A‑2, B, C and C‑1 Preferred Stock was equal to the original issuance price of the preferred stock plus any accrued or declared but unpaid cumulative dividends. The redemption price of the Series D and D‑1 Preferred Stock was the greater of (i) the fair market value of the common stock which it was convertible into or (ii) the original issuance price plus all declared but unpaid dividends, which were non-cumulative. As of December 31, 2016, the fair market value of the Company’s common stock was less than the original issuance price of the Series D Preferred Stock.

Preferred stock was presented in mezzanine equity. The Series A‑1, A‑2, B, C, C‑1, D and D‑1 Preferred Stock were redeemable at the option of the holder at a fixed date and therefore the Company was accreting the preferred stock to its redemption value through the earliest possible redemption date for all issuances where the carrying value is less than the redemption value. The Series A‑3 Preferred Stock was redeemable only upon certain deemed liquidation scenarios which were outside of the Company’s control. The accretion included the accretion of issuance costs and cumulative preferred stock dividends. Series A‑3 Preferred Stock was not entitled to dividends. The Company assessed all terms and features of the preferred stock in order to identify any potential embedded features that would require bifurcation or any beneficial conversion features. As part of this analysis, the Company assessed the economic characteristics and risks of its preferred stock, including conversion and liquidation features, as well as dividend and voting rights. The Company determined that all features of the preferred stock were clearly and closely associated with an equity host, and although the preferred stock included conversion features, such conversion features did not require bifurcation as a derivative liability. On the date of issuance, the fair value of common stock into which the Series A‑1, A‑2, A‑3, B, C, C‑1, D and D‑1 Preferred Stock was convertible was less than the effective conversion price of the Series A‑1, A‑2, A‑3, B, C, C‑1, D and D‑1 Preferred Stock and as such, there was no intrinsic value of the conversion option at the commitment date.

Upon completion of the IPO on December 7, 2017 all outstanding shares of Preferred Stock were automatically converted into shares of common stock on a 3.214‑for-one basis, resulting in the issuance of 14,185,744 shares of common stock. Details of the shares of Preferred Stock converted to common stock upon the completion of the IPO by class of Preferred Stock is as follows:


		Shares of
		Preferred
Preferred Stock		Stock
A‑1		3,972,415
A‑2		10,427,586
A‑3		2,000,000
B		6,021,636
C		8,092,895
C‑1		544,332
D		12,420,262
D‑1		2,113,902
Total		45,593,028

Pursuant to the amended and restated certificate of incorporation filed in connection with the IPO in December 2017, the Company authorized 5,000,000 shares of preferred stock. The amended and restated certificate of incorporation authorized our board of directors, without any further stockholder action or approval, to issue these shares in one or more classes or series, to establish from time to time the number of shares to be included in each class or series and to fix the rights, preferences and privileges of the shares of each wholly unissued class or series and any of its qualifications, limitations or restrictions. There was no preferred stock issued or outstanding as of December 31, 2017.

The Company has a class of authorized preferred stock amounting to 5,000,000 shares as of December 31, 2018 and December 31, 2017. The authorized preferred stock was classified under stockholders’ equity at December 31, 2018 and December 31, 2017.

Prior to the IPO in December 2017, the Company had multiple classes of preferred stock outstanding. These shares of preferred stock were converted to shares of common stock at the time of the IPO on 1‑for‑3.214 shares basis. The reconciliation of net loss attributable to common shareholders in the consolidated statement of operations for the year ended December 31, 2017 includes an adjustment for accretion of preferred stock to redemption value.

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units

12 Months Ended

Dec. 31, 2018

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units

8. Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units

Common stock reserved

The Company reserved the following shares of common stock, on a common stock equivalent basis, for the conversion of shares of preferred stock, the exercise of warrants, the exercise of common stock options, and the vesting of restricted common stock.


	Year ended December 31,
	2018	2017
Common stock warrants	76,041	86,090
Common stock options and unvested restricted common stock	2,838,402	2,427,035
Shares reserved for future awards under compensation plan	2,433,999	3,500,620
	5,348,442	6,013,745

Warrants

The following tables summarize the Company’s outstanding warrants as of December 31, 2018, and 2017:


		Weighted
	Issued and	Average
	exercisable	Exercise Price
As of December 31, 2017	86,090	$	9.14
Issued	10,000		4.83
Exercised	(16,718)		11.73
Cancelled	(3,331)	$	11.73
As of December 31, 2018	76,041		10.10

The Company has an agreement with a vendor (Note 7) where the Company could be obligated to issue warrants to purchase an additional 93,341 shares of common stock to the vendor if the contract is terminated prior to a minimum purchase commitment being met. No shares have been reserved related to these potential obligations to issue warrants in the future. On January 30, 2018, the company issued a warrant to purchase 10,000 of common stock to a consultation company for services rendered.

Stock-based compensation

Share-based compensation expense for all stock awards consists of the following (in thousands):


	Year ended December 31,
	2018		2017		2016
Cost of product revenue	$	55	$	24	$	6
Cost of service and other revenue		173		52		12
Research and development		513		180		59
General and administrative		4,143		1,912		851
Total	$	4,884	$	2,168	$	928

In June 2007, the Company adopted the 2007 Stock Option and Grant Plan (the 2007 Plan), under which it could grant incentive stock options, non-qualified options, restricted stock, and stock grants. At December 31, 2016, the 2007 Plan allowed for the issuance of up to 3,229,935 shares of common stock. During the three months ended March 31, 2017, the 2007 Plan was amended to allow for the issuance of an additional 622,227 shares of common stock for a total issuance of up to 3,852,213 shares of common stock at June 30, 2017. During the three months ended September 30, 2017 the 2007 Plan was further amended to allow for the issuance of an additional 497,822 shares of common stock for total issuance of up to 4,350,035 shares of common stock at September 30, 2017. As of December 31, 2017, under the 2007 Plan, options to purchase 2,249,843 shares of our common stock were outstanding, 571,838 shares of our common stock had been issued and were outstanding pursuant to the exercise of options, 1,128,975 shares of our common stock had been issued and were outstanding pursuant to restricted or unrestricted stock awards, and 399,379 shares of our common stock were available for future awards. In connection with the completion of the IPO, the Company terminated the 2007 Plan.

In December 2017, the Company adopted the 2017 Employee, Director and Consultant Equity Incentive Plan (the 2017 Plan), under which it may grant incentive stock options, non-qualified stock options, restricted stock, and other stock-based awards. As of December 31, 2017, the 2017 Plan allowed for the issuance of up to 1,042,314 shares of common stock plus up to 2,490,290 shares of our common stock represented by awards granted under the 2007 Plan that are forfeited, expire or are cancelled without delivery of shares or which result in the forfeiture of shares of common stock back to the Company on or after the date the 2017 Plan becomes effective. As of December 31, 2018 and 2017, there were shares available for grant under the 2017 Plan of 4,393 and 1,042,314, respectively.

In addition, the 2017 Plan contains an "evergreen" provision, which allows for an annual increase in the number of shares of common stock available for issuance under the 2017 Plan on the first day of each fiscal year during the period beginning in fiscal year 2019 and ending in fiscal year 2027. The annual increase in the number of shares shall be equal to the lowest of: 4% of the number of shares of common stock outstanding as of such date; and an amount determined by the Company’s Board of directors or Compensation Committee. On January 1, 2019, the number of shares of common stock available for issuance under the 2017 plan was automatically increased by 895,169 shares.

In December 2017, the Company adopted the 2017 Employee Stock Purchase Plan (the 2017 ESPP). As December 31, 2017, the 2017 ESPP allowed for the issuance of up to 208,463 shares of common stock. As of December 31, 2018, 425,533 shares were available for grant under the 2017 ESPP.

In addition, the 2017 ESPP contains an "evergreen" provision, which allows for an increase on the first day of each fiscal year beginning with fiscal year 2018. The increase in the number of shares shall be equal to the lowest of: 1% of the number of shares of common stock outstanding on the last day of the immediately preceding fiscal year or an amount determined by the Company’s Board of Directors or Compensation Committee.

The 2017 ESPP provides for six-month option periods Commencing on March 1 and ending August 31 and Commencing September 1 and ending February 28 of each calendar year. The first offering under the 2017 ESPP began on September 1, 2018.

Stock options

Under the 2007 and 2017 Plans, stock options may not be granted with exercise prices of less than fair market value on the date of the grant. Options generally vest ratably over a four-year period with 25% vesting on the first anniversary and the remaining 75% vesting ratably on a monthly basis over the remaining three years. These options expire ten years after the grant date. Activity under the 2007 and the 2017 Plans was as follows:


		Weighted-		Remaining	Aggregate
		average		contractual	intrinsic
		exercise		life	value
	Options	price		(in years)	(in thousands)
Outstanding at December 31, 2016	1,119,671	$	2.99	6.8		5,796
Granted	1,281,135	$	8.46
Exercised	(90,265)	$	2.25
Cancelled or forfeited	(60,698)	$	6.16
Outstanding at December 31, 2017	2,249,843	$	6.05	7.8		34,695
Granted	729,224	$	18.36
Exercised	(407,901)	$	4.57
Cancelled or forfeited	(94,255)	$	13.16
Outstanding at December 31, 2018	2,476,911	$	9.65	7.733	$	22,108
Vested and expected to vest at December 31, 2018	2,476,911	$	9.65	7.733	$	22,108
Exercisable at December 31, 2018	1,143,480	$	5.68	6.514	$	14,440

Using the Black-Scholes option pricing model, the weighted-average fair value of options granted to employees and directors during the years ended December 31, 2018, 2017, and 2016 was $ 7.19, $4.52, and $2.41 per share, respectively. The expense related to awards granted to employees was $2.7 million, $1.5 million, and $0.2 million for the years ended December 31, 2018, 2017, and 2016. The intrinsic value of stock options exercised was $5.3 million, $1.1 million, and $0.4 million, for the years ended December 31, 2018, 2017, and 2016, respectively. Activity related to non-employee awards was not material to the years ended December 31, 2018, 2017, and 2016.

At December 31, 2018, there was $6.8 million of total unrecognized compensation cost related to unvested stock options, which is expected to be recognized over the remaining weighted-average vesting period of 2.23 years.

Restricted Stock Awards

In December 2014, the Company issued 78,912 shares of restricted common stock to a director of the Company under the 2007 Plan. Under the terms of the agreement, shares of common stock issued are subject to a four year vesting schedule. Vesting occurs periodically at specified time intervals and specified percentages. In January 2015, the Company issued 781,060 shares of restricted common stock to an executive of the Company under the 2007 Plan. The majority of these shares were issued subject to a four year vesting schedule with 25% vesting on the first anniversary and the remaining vesting 75% ratably on a monthly basis over the remaining three years, while another portion was issued subject to performance based vesting. The vesting of performance based awards is dependent upon achievement of specified financial targets of the Company. The majority of the performance criteria were achieved during the years ended December 31, 2016 and 2015 and the remaining unvested awards with performance conditions are not material. No restricted stock awards were granted during the years ended December 31, 2018 or 2017. A summary of restricted stock activity is as follows:


		Weighted-average
		grant date
		fair value
	Shares	per share
Unvested restricted common stock as of December 31, 2015	623,869	3.12
Vested	(247,621)	3.09
Unvested restricted common stock as of December 31, 2016	376,248	3.12
Vested	(199,056)	3.12
Unvested restricted common stock as of December 31, 2017	177,192	3.11
Vested	(137,386)	3.11
Unvested restricted common stock as of December 31, 2018	39,806	3.12

The expense related to awards granted to employees and directors was $0.4 million, $0.6 million, and $0.7 million for the years ended December 31, 2018, 2017, and 2016, respectively.

At December 31, 2018, there was $0 million of total unrecognized compensation cost related to unvested restricted stock, which is expected to be recognized over the remaining weighted-average vesting period of 0 years.

The aggregate fair value of restricted stock awards that vested during the years ended December 31, 2018, 2017, and 2016, based on estimated fair values of the stock underlying the restricted stock awards on the day of vesting, was $2.4 million, $1.9 million and $1.1 million, respectively.

Restricted stock units

Restricted stock units represent the right to receive shares of common stock upon meeting specified vesting requirements. In the fiscal year ended December 31, 2018, the Company issued 422,027 restricted stock units to employees of the Company under the 2017 Plan. Under the terms of the agreements, 84,637 of the restricted stock units issued are subject to a four year vesting schedule with 25% vesting on the first anniversary and the remaining vesting 75% ratably on a monthly basis over the remaining three years, 18,200 of the restricted stock units issued are subject to vesting with 50% vesting on December 31, 2018 and 50% vesting on December 31, 2019, 3,300 of the restricted stock units are subject to a four year vesting schedule with 25% vesting on each anniversary, 15,890 of the restricted stock units vest on December 31, 2018, 50,000 of the restricted stock units vested on August 31, 2018, and 250,000 of the restricted stock units vest evenly over 40 months on the last day of each month starting September 30, 2018. A summary of restricted stock unit activity is as follows:


		Weighted-average
		grant date
		fair value
	Shares	per share
Unvested restricted stock units as of December 31, 2017	—
Granted	422,027	$	15.65
Vested	(99,990)	$	15.02
Cancelled or Forfeited	(375)	$	18.40
Unvested restricted stock units as of December 31, 2018	321,662	$	15.84

The expense related to awards granted to employees and directors was $1.7 the fiscal year ended December 31, 2018.

At December 31, 2018, there was $4.9 million of total unrecognized compensation cost related to unvested restricted stock, which is expected to be recognized over the remaining weighted-average vesting period of 0.6 years.

Commitments and contingencies

12 Months Ended

Dec. 31, 2018

Commitments and contingencies

Commitments and contingencies

9. Commitments and contingencies

License agreements

Tufts University

In June 2007, the Company entered into a license agreement (the License Agreement) for certain intellectual property with Tufts University (Tufts). Tufts is a related party to the Company due to Tuft’s equity ownership in the Company and because a board member of the Company’s Board of Directors was affiliated with Tufts. The License Agreement, which was subsequently amended, is exclusive and sub licensable, and will continue in effect on a country by country basis as long as there is a valid claim of a licensed patent in a country. The Company is committed to pay license and maintenance fees, prior to commercialization, in addition to low single digit royalties on direct sales and services and a royalty on sublicense income. During the year ended December 31, 2016, the Company executed a license agreement with a diagnostic company and also amended the bioMérieux agreement (Note 11). During the years ended December 31, 2018, 2017 and 2016, the Company recorded royalty expense of $0.7 million, $0.5 million and $0.3 million, respectively, in cost of product revenue on the consolidated statements of operations and comprehensive loss.

Other licenses

During the year ended December 31, 2012, the Company entered into a license agreement for certain intellectual property with a third party. The non-exclusive, non-sublicenseable third party’s license provides the Company access to certain patents specifically for protein detection, and shall be in effect until the expiration of the last licensed patent. In consideration for these rights, the Company committed to certain license fees, milestone payments, minimum annual royalties and a mid-single digit royalty. The Company is required to make mid-single digit royalty payments on net sales of products and services which utilize the licensed technology. The Company must pay the greater of calculated royalties on net sales or an annual minimum royalty of $50 thousand. During the year ended December 31, 2018, 2017 and 2016, the Company recorded royalty expense of $0.4 million, $0.2 million, and $0.2 million, respectively, in cost of product revenue on the consolidated statements of operations.

Lease commitments

During the year ended December 31, 2014, the Company entered into a lease agreement for the Company’s current corporate headquarters with a lease term that expires in June 2020; however, in November 2018, the Company agreed to terminate the lease with the lessor effective May 2019. The termination of the lease was connected to the Company signing a new lease in Billerica, MA. On October 2, 2018, the Company entered into a 137 month operating lease for the Company’s new headquarters in Billerica, MA. The lease is for approximately 92,000 square feet of office and laboratory space, and will commence on or about April 1, 2019. The lease contains a period of free rent and escalating monthly rent payments. As part of the lease, the Company was required to enter into a $1.0 million Letter of Credit drawable by the lessor under specifically outlined conditions. The amount of the Letter of Credit will be reduced at 41 and 65 months after the commencement date of the lease to $750,000 and then $250,000, respectively. The $1 million Letter of Credit is recorded as restricted cash on the balance sheet.

In connection with the acquisition of Aushon in January 2018, the Company assumed the existing Aushon lease for facilities in Billerica, Massachusetts. In August 2018 the Company terminated the Aushon lease effective September 1, 2019. The Company is required to pay a termination fee no later than July 1, 2019 in consideration for the early termination.

Rent expense is recognized straight-line over the course of the lease term. As of December 31, 2018, $0.3 million of deferred rent expense was recorded in other non-current liabilities, and less than $0.1 million was recorded in other accrued expenses. The table below includes committed lease expenditures related to the new lease.

As of December 31, 2018, the minimum future rent payments under the lease agreements are as follows (in thousands):


Years ending December 31:
2019	$	1,172
2020		2,013
2021		3,290
2022		3,372
2023 and Forward		29,207
	$	39,054

The Company recorded $1.6 million, $1.1 million and $1.1 million in rent expense for the years ended December 31, 2018, 2017 and 2016, respectively.

Development and supply agreement

Through the Company’s development agreement with STRATEC Biomedical, as amended in December 2016, the parties agreed on additional development services for an additional fee, which is payable when the additional development is completed. A total of $1.5 million is payable to STRATEC upon completion of the development activities. This amount is being recorded to research and development expense and accrued expenses as the services are performed. The services were completed during the year ending December 31, 2018. Substantive efforts related to these additional development activities started in the first quarter of 2017.

The Company’s supply agreement with STRATEC Biomedical requires the Company to purchase a minimum number of commercial units over a seven-year period ending in May 2021. If the Company were to fail to purchase a required number of commercial units, the Company would be obligated to pay termination costs plus a fee based on the shortfall of commercial units purchased compared to the required minimum amount. Based on the number of commercial instruments purchased as of December 31, 2018, assuming no additional commercial units were purchased, this fee would equal $11.1 million. The amount the Company could be obligated to pay under the minimum purchase commitment is reduced as each commercial unit is purchased. Also, if the Company terminates the Supply Agreement under certain circumstances and has not purchased a required number of commercial units, it would be obligated to issue warrants to purchase 93,341 shares of common stock (the Supply Warrants) at $0.003214 per share. The Company believes that it will purchase sufficient units to meet the requirements of the minimum purchase commitment and, therefore, has not accrued for any of the potential cash consideration. The Supply Warrants are accounted for at fair value; however, the fair value of the Supply Warrants as of December 31, 2018 and December 31, 2017 was insignificant as there was a low probability of the warrants being issued.

Legal contingencies

The Company is subject to claims in the ordinary course of business; however, the Company is not currently a party to any pending or threatened litigation, the outcome of which would be expected to have a material adverse effect on its financial condition or the results of its operations. The Company accrues for contingent liabilities to the extent that the liability is probable and estimable.

Long Term Debt

12 Months Ended

Dec. 31, 2018

Long Term Debt

Long Term Debt

10. Long Term Debt

Loan agreement

On April 14, 2014, the Company executed a Loan Agreement with a lender, as subsequently amended in March 2015, January 2016, March 2017, August 2018, and October 2018. As of December 31, 2018, there were no additional amounts available to borrow under the debt facility. The interest rate on this term loan is variable based on a calculation of the prime rate less 5.25% with a minimum interest rate of 8%. Interest is paid monthly beginning the month following the borrowing date. At loan inception and in connection with the amendments, the Company issued the lender warrants to purchase shares of stock. The Loan Agreement also contains prepayment penalties and an end of term charge. Fees incurred in execution of the agreements, and the fair value of warrants on the date of grant were accounted for as a reduction in the book value of debt and accreted through interest expense, using the effective interest rate method, over the term of the debt.

In connection with the Loan Agreement, the Company granted the lender warrants to purchase shares of either Series C Preferred Stock or shares of preferred stock in the next financing round. Following the completion of the IPO, these warrants became exercisable for shares of the Company’s common stock. Therefore, additional warrants will be issued if the Company draws on any of the remaining debt facility. The warrants issued in connection with the initial borrowing were initially recorded at fair value of $0.1 million as a preferred stock warrant liability in the accompanying consolidated balance sheets and a corresponding debt discount was recorded. The Company has not further drawn on the remaining debt facility.

The Company also incurred debt issuance costs of $0.1 million. As a result of the debt discounts recorded related to the warrants and the debt issuance costs, the debt was initially recorded at less than its face value. The debt, including the end of term charge, is being accreted over the life of the loan using the effective interest method.

The Loan Agreement also provided the lender with a right to invest up to $1.0 million or, subject to Company approval and consent, to convert up to $1.0 million of outstanding principal into shares of preferred stock in the next financing round at the same price as all other investors. The lender invested $1.0 million in March 2016 as part of the Series D Preferred Stock financing.

Amendment 1 to loan agreement

On March 4, 2015, the Company executed Amendment 1 to the Loan Agreement (Amendment 1) and borrowed the remaining $5.0 million that was available under the loan facility. The terms of Amendment 1 allowed the Company to defer the commencement of principal payments to December 1, 2015 and extended the loan maturity date to February 1, 2018. If the Company obtained at least $10.0 million in equity financing before December 1, 2015, the commencement of principal payments could be further deferred until March 1, 2016 and the loan maturity date could be extended to May 1, 2018. As the financing milestone was not achieved, the Company made the first principal payment of $0.3 million on December 1, 2015 and the loan maturity date was February 1, 2018 under Amendment 1.

The additional $5.0 million borrowed included an additional $0.2 million end of term charge. The end of term charge on this borrowing is being accreted over the life of the loan as additional interest expense. The additional borrowing also resulted in the issuance of additional warrants with a grant date fair value of $0.1 million. The fair value of the additional warrants were initially recorded at fair value as a preferred stock warrant liability in the accompanying consolidated balance sheets and a corresponding debt discount was recorded. The debt, including the end of term charge, is being accreted over the remaining life of the loan using the effective interest method.

Amendment 2 to loan agreement

In January 2016, the Company executed Amendment 2 to the Loan Agreement (Amendment 2). Amendment 2 increased the total facility available by $5.0 million to a total of $15.0 million and further delayed the commencement of principal payments to July 1, 2016. Under Amendment 2, following the Series D Preferred Stock financing (Note 8), the Company could have elected to further delay the commencement of principal payments until January 1, 2017, however the Company voluntarily began paying principal on July 1, 2016. Upon signing Amendment 2, the Company drew an additional $3.0 million under the debt facility. The remaining $2.0 million available under the facility expired unexercised in April 2016, which reduced the amounts available under the facility to $13.0 million.

The additional $3.0 million borrowed included an additional $0.1 million end of term charge. The end of term charge on this borrowing is being accreted over the life of the loan. The additional borrowing also resulted in the issuance of additional warrants with a grant date fair value of $0.1 million. The fair value of the additional warrants were initially recorded at fair value as a preferred stock warrant liability in the accompanying consolidated balance sheets and a corresponding debt discount was recorded. The debt, including the end of term charge, is being accreted to over the remaining life of the loan using the effective interest method.

Amendment 3 to loan agreement

In March 2017, the Company signed Amendment 3 to the Loan Agreement (Amendment 3). Amendment 3 increased the total facility available by $5.0 million to a total of $18.0 million. Additionally, the lender may provide an additional optional term loan, solely at the lender’s discretion, for an incremental $5.0 million, increasing the total potential facility to $23.0 million. As of December 31, 2017, the Company has not drawn any of this additional facility. The terms of Amendment 3 allowed the Company to defer the commencement of principal payments to March 1, 2018 and extended the loan maturity date to March 1, 2019. Amendment 3 did not change the due date of the existing end of term fees of $0.05 million which remained due on February 1, 2018. Upon signing Amendment 3, the Company did not draw any of the additional amounts available under the amended debt facility and no amounts have been subsequently drawn under the facility. The Company has until September 3, 2018 to draw the additional amounts.

Amendment 4 to loan agreement

In July 2017, the Company signed Amendment 4 to the Loan Agreement (Amendment 4). Amendment 4 instituted a cap of 10% with respects to the “Term Loan Interest Rate”.

Amendment 5 to loan agreement

In August 2018, the Company signed Amendment 5 to the Loan Agreement (Amendment 5). Amendment 5 instituted a 2018 End of Term Charge of $0.08 million. Additionally, the Term Loan Maturity Date was amended to be extended until March 1, 2020. Amendment 5 additionally, changed the due date of the End of Term Charge to, the earlier of (i) the Term Loan Maturity Date, (ii) the date that Borrower prepays the outstanding Secured Obligations or (iii) the date that the Secured Obligations become due and payable. The Company incurred a cost of $0.05 million in relation to the execution of Amendment 5. In connection with the extension of the due date of the Loan, the deferral of principal payments (Amendment 3) was further deferred until the new Term Loan Maturity Date.

Amendment 6 to loan agreement

In October 2018, we signed Amendment 6 to the Loan agreement, which amends the Loan Agreement’s collateral clause to exclude the $1 million certificate of deposit associated with the lease on our new headquarters in Billerica, MA.

End of term charges related to the facility of $0.5 million, and principal payments of $1.4 million were paid during the fiscal year ended December 31, 2018. Under the terms of the August 2018 amended agreement, principal payments were delayed until March 2020. The Company accounted for the August 2018 amendment as a modification as it was determined that no material change occurred as a result of the modification. The Company voluntarily made principal payments in the months of March, April, and May, 2018. No principal payments were made in June, July or August, 2018. Under the amended Loan Agreement, the remaining outstanding principal will be paid upon maturity of the note in March 2020. As of December 31, 2018, the remaining loan balance is classified as a long term liability since all principal payments are due greater than twelve months after the balance sheet date.

Debt payment obligations due based on principal payments are as follows (in thousands):


Years ending December 31:
2019	$	0
2020		7,763
	$	7,763

The balance sheet contains $0.1 million of unamortized debt issuance costs which nets the Long Term Debt balance to $7.6 million. Non-cash interest expense related to debt discount amortization and accretion of end of term fees was $0.2 million, $0.2 million, and $0.4 million for the year ended December 31, 2018, 2017, and 2016, respectively.

The Company assessed all terms and features of the Loan Agreement and the subsequent amendments in order to identify any potential embedded features that would require bifurcation. As part of this analysis, the Company assessed the economic characteristics and risks of the debt. The Company determined that all features of the Loan Agreement and the subsequent amendments are either clearly and closely associated with a debt host or have a de minimis fair value and, as such, do not require separate accounting as a derivative liability. The Company assessed each amendment under ASC 470‑50 and concluded that all of the amendments constituted modifications. In this analysis, consideration was given to the fact that Amendments 4, 5, and 6 were executed within one year of each other. The Company also assessed whether the amendments represented a troubled debt restructuring and concluded they did not. The Company accounted for each of the amendments to the Loan Agreement as a modification of its debt and the unamortized discount and issuance costs related to the prior debt are amortized over the modified term of the new debt.

The Loan Agreement and the subsequent amendments contain negative covenants restricting the Company’s activities, including limitations on dispositions, mergers or acquisitions, incurring indebtedness or liens, paying dividends or making investments and certain other business transactions. There are no financial covenants associated with the Loan Agreement and the subsequent amendments. The obligations under the Loan Agreement and subsequent amendments are subject to acceleration upon the occurrence of specified events of default, including a material adverse change in the Company’s business, operations or financial or other condition. The Company has determined that the risk of subjective acceleration under the material adverse events clause is not probable and therefore has classified the outstanding principal in current and long-term liabilities based on scheduled principal payments.

Collaboration and license arrangements

12 Months Ended

Dec. 31, 2018

Collaboration and license arrangements

Collaboration and license arrangements

11. Collaboration and license arrangements

In November 2012, the Company entered into the JDLA with bioMérieux, a related party. As discussed below, the JDLA has been subsequently amended. Under the terms the JDLA, the Company granted bioMérieux an exclusive, royalty-bearing license, without right to sublicense, to manufacture and sell instruments and assays using our Simoa technology exclusively for in vitro diagnoses used in clinical lab applications, food quality control testing, and pharma quality control testing, and co-exclusively in certain related fields, as defined in the contract. As part of the JDLA, the Company was also to develop and manufacture instruments to bioMérieux’s specifications for bioMérieux’s use or for sale by bioMérieux. The Company retained rights to sell the instrument in the co-exclusive fields and any other fields not licensed exclusively to bioMérieux. bioMérieux was to develop and sell diagnostic assays to be used in conjunction with the Company’s instruments.

Upon execution of the JDLA, the Company received $10.0 million in consideration and was entitled to receive two additional payments of $5.0 million each upon the achievement of certain developmental criteria. Neither of these criteria have been achieved. The Company was also entitled to receive royalty payments on the sale of assays and payments for the manufacture and delivery of instruments based on a contractual rate subject to future adjustments.

At the inception of the JDLA, the Company determined that the deliverables were as follows: (1) licenses to the Company’s technology and trademarks, training, completion and delivery of a prototype instrument per contractual specifications (License and Prototype), (2) various activities to assist bioMérieux in the development of the initial assay and an instrument that is IVD compliant (Initial Assay Assistance), (3) various activities to assist bioMérieux in the development of a benchtop instrument (Benchtop Assistance), and (4) joint steering committee participation (JSC). Each of these deliverables were considered separate units of accounting, and the License and Prototype unit of accounting was determined to have standalone value as the License and Prototype unit of accounting could be utilized by bioMérieux without the related services included in the other units of accounting.

The Company allocated the allocable arrangement consideration based on the relative selling price of each unit of accounting. For all units of accounting, the Company determined the selling price using the best estimate of selling price (BESP). Management’s best estimate of the selling price of the License and Prototype unit of accounting was based on a discounted cash flow analysis to support the estimated selling price of the license. The Company determined the BESP of the other units of accounting based on internal estimates of the costs to perform the services, adjusted to reflect a reasonable profit margin as well as based on market prices for similar instruments and services.

Revenue related to the License and Prototype unit of accounting of $8.3 million was recognized in 2013 upon delivery of both the license which was delivered at inception, and the first prototype instrument, which was required for bioMérieux to make use of the license. Prior to the effect of the 2016 Amendment described below, revenue for the other units of accounting were recognized over an estimated period of performance.

Amendments to the JDLA

In May 2014 and January 2015, the parties executed a First and Second Amendment to the JLDA, respectively. These amendments addressed revised timelines related to completing the development activities under the JDLA and enacted additional governance protocols to monitor those activities.

These amendments did not change the deliverables under the JDLA or the total arrangement consideration. The Company revised its estimates of the remaining period of performance for the remaining undelivered units of accounting and these revisions did not have a material effect on revenue recognition.

On December 22, 2016, the Company entered into the 2016 Amendment which ended the ongoing joint development efforts between the parties, and modified the rights and obligations of both parties accordingly, as follows:

For a period of not more than three years from the date of the 2016 Amendment bioMérieux has the ability to evaluate independently whether it will develop a new, smaller in vitro diagnostic instrument using the Simoa technology for use in clinical lab applications, food quality control testing, and pharmaceutical quality control testing benchtop (the "Feasibility Period") and has the sole right to determine whether or not to develop such a new instrument during the Feasibility Period. If bioMérieux does elect to pursue development of such a new instrument, they will have a set number of years to complete development within a specified period, which contains various development milestones which must be accomplished.

bioMérieux received a license to the source and object code of the Company’s Level 1 Data Reduction (L1DR) software. The L1DR software the Company’s proprietary image processing algorithms that convert images of microscopic beads associated with biomarker molecules in microwells. Also, the Company must provide to bioMérieux access to any know how and intellectual property associated with the L1DR software, including any updates and upgrades to the L1DR software during the Feasibility Period. If bioMéreiux exercises its right to develop an instrument independently, this right will continue throughout the development period to the end of the term of the agreement related to independently developed instruments.

It was clarified that the Company can engage a collaboration partner (IVD Partner), subject to restrictions as to the particular parties with which the Company could elect to partner and the assays that can be developed, in the field of in vitro diagnostics used in Clinical Lab Applications. The Company shall pay bioMérieux a mid-double-digit percentage of royalties received from the IVD Partner based on assays sales by the IVD Partner.

bioMérieux’s licenses include all patents and know-how owned or controlled by the Company related to the Company’s Simoa technology and upgrades thereto that are necessary for the development, manufacture, use or sale of instruments and assays or consumables on such instruments over the Feasibility Period. If bioMérieux exercises its right to develop an instrument independently, this right will continue throughout the development period to the end of the term of the 2016 Amendment related to independently developed instruments.

bioMérieux retains an option (the Option) to obtain worldwide distribution rights to the HD‑1 floor standing instrument in the applicable fields. The Option is exercisable over a three year period and upon exercise, the Company and bioMérieux are required to negotiate, in good faith, a distribution agreement that would include a specified upfront payment.

The 2016 Amendment included a cash payment of $2.0 million from bioMérieux which was paid in January 2017.

On September 6, 2018, bioMérieux notified the Company that it was terminating the Amended JDLA, forfeiting any future IVD licensing rights to the Company’s Simoa technology and enabling the Company to consolidate and regain control of all Simoa IVD licensing and IP rights.

Accounting assessment

Prior to the execution of the 2016 Amendment, the Company was recognizing revenue over the estimated period of performance of the ongoing units of accounting (Initial Assay Assistance, Benchtop Assistance, and JSC). As a result, the Company recognized $0.2 million and $0.2 million in revenue for the years ended December 31, 2015 and 2016, respectively. At the date of the execution of the 2016 Amendment, the Company had $1.2 million in deferred revenue related to the JDLA. Upon the execution of the 2016 Amendment, all undelivered elements and contingent consideration of the JDLA were cancelled. The Company determined the 2016 Amendment should be accounted for as a modification to the JDLA and the balance of deferred revenue prior to the 2016 Amendment should be included as allocable consideration under the 2016 Amendment resulting in total allocable consideration of $3.2 million. The Company recorded an increase to deferred revenue upon receipt of the $2.0 million during the three months ended March 31, 2017.

The Company has determined that the deliverables included under the 2016 Amendment are rights to the L1DR software, training and rights to future technology improvements for L1DR Software, rights to all future technological improvements related to the Simoa technology, and participation on joint committees.

The Company determined that the L1DR and rights to unspecified technology improvements (the "L1DR Unit of Accounting") includes the sale of software and software related elements and therefore should be accounted for under ASC 985‑605—Software Revenue Recognition. The Company cannot demonstrate Vendor Specific Objective Evidence (VSOE) of fair value for the ongoing obligation to provide unspecified technology improvements. Therefore, the deliverables in the L1DR Unit of Accounting cannot be separated. The Company has applied the combined service approach and the consideration allocated to this unit of accounting is being recognized ratably over the estimated period of performance, which has initially been determined to be estimated to be the three year Feasibility Period. This will be reevaluated each period to determine if there are any changes to the estimated period of performance.

The Company concluded that the rights to future technology improvements for the Simoa technology and the participation on joint committees represented a second unit of accounting (the "Instrument Know How Unit of Accounting"). The deliverables in the Instrument Know How Unit of Accounting are considered non-software deliverables that are subject to ASC 605‑25 and will be delivered over time on a when and if available basis. Revenue is being recognized on a straight line basis over the estimated period of performance, which has initially been determined to be the three year Feasibility Period. This period will be reevaluated each period to determine if there are any changes to the period of performance.

The Option is considered substantive as the Company is at risk with regard to whether bioMérieux will exercise the Option. In addition, the Option exercise payment payable by bioMérieux upon exercise is not priced at a significant and incremental discount. Accordingly, the Option is not considered a deliverable at the inception of the arrangement and the associated Option exercise payment is not included in allocable arrangement consideration.

Under the 2016 Agreement the Company is eligible to receive royalties on net sales of assays sold by bioMérieux in the mid to high single digits, and to receive low double digit royalties on sales of instruments by bioMérieux based on manufactured cost. No royalties have been recognized through December 31, 2018.

Upon termination of the agreement, the Company no longer held an obligation to bioMérieux related to the initial agreement or the amendment to the agreement. As such, the Company immediately recognized all remaining deferred revenue related to the agreements as of the date of termination.

The Company recognized revenue of $2.1 million and $1.1 million for the years ended December 31, 2018 and 2017, respectively, as collaboration revenue.

Evaluation and option agreements and license agreement

In 2015, the Company entered into three agreements, for three separate fields, with a diagnostic company for the evaluation of the Company’s Simoa technology. These agreements each allowed for the option to negotiate a license agreement. In return, the Company received non-refundable payments totaling $2.0 million. In December 2016, the diagnostic company exercised one of its options and the parties entered into a license agreement in one of the fields. This agreement has a one-time non-refundable license fee of $1.0 million and the right to receive running low single digit royalties on licensed products. The negotiation periods for the other two agreements were extended and the negotiations remain ongoing.

For each of the three fields, the right to evaluate the technology, the right to negotiate a license to the technology, and the undelivered license to the technology represents a combined unit of accounting, and the licenses to each of the three fields each have standalone value. The Company has allocated the allocable arrangement consideration based on the relative selling price of each unit of accounting. The BESP of each of the three options was determined to be representative of the contractual amount paid for each option. The Company defers the amounts allocated to each of the three options until the corresponding license is delivered or, if no license agreement is executed and delivered, when the negotiations for each option terminates.

Upon execution of the license in one of the fields in December 2016, the $1.0 million license fee, in addition to the $0.8 million allocated to the option for this field, resulted in a total of $1.8 million of consideration being recognized as revenue as there were no remaining undelivered performance obligations. Because the negotiations remain ongoing with respect to the other two fields, the consideration allocated to these options of $1.2 million has been deferred and is recorded as deferred revenue as of December 31, 2017.

In December 2018 the Company entered into an option agreement for the rights to negotiate an exclusive agreement with the diagnostic company. In exchange for the rights to negotiate an exclusive agreement, the Company will receive $0.5 million in consideration. As the right to negotiate with the Company has not been executed, the consideration from this agreement is deferred until the sooner of the execution of the contract or the end of the option period.

Employee benefit-plans	12 Months Ended
Employee benefit-plans	Dec. 31, 2018
Employee benefit-plans
Employee benefit-plans	12. Employee benefit-plans The Company sponsors a 401(k) savings plan for our employees The Company may make discretionary contributions for each 401(k) plan year. During the year ended December 31, 2018 the Company made contributions of $0.1 million and during the year ended December 31, 2017 and 2016 did not make any contribution.

Business combinations

12 Months Ended

Dec. 31, 2018

Business combinations

Business combinations

13. Business combinations

On January 30, 2018, the Company completed the acquisition of Aushon pursuant to an Agreement and Plan of Merger dated January 30, 2018 (the “Aushon Acquisition”). The Company acquired Aushon to complement its existing product line, improve its existing research and development capabilities in assay development and software engineering, and expand its customer base. The Aushon Acquisition has been accounted for as a business combination and the Company has recorded the assets acquired and liabilities assumed at their respective fair values as of the acquisition date.

In connection with the closing of the Aushon Acquisition, the Company paid $3.2 million at closing, and an additional $0.8 million in July 2018, the six-month anniversary of the acquisition date.

The following table presents the allocation of the purchase consideration for the transaction as of January 30, 2018 including the allocation of the purchase consideration (in thousands):


Fair value of consideration transferred:
Cash	$	3,200
Obligation to issue cash		800
Total acquisition consideration	$	4,000

Fair value of assets acquired and liabilities assumed:
Cash and cash equivalents	$	199
Accounts receivable		210
Inventory		828
Prepaid expenses		71
Property and equipment and other non-current assets		180
Intangible Assets		2,950
Goodwill		1,308
Total assets acquired		5,746
Contractual obligations		(1,155)
Accounts payable and accrued liabilities		(591)
Net assets acquired	$	4,000

The intangible assets identified in the purchase price allocation discussed above include developed technology, tradenames and customer relationships. Tradenames are amortized over the useful life on a straight-line basis, while developed technology and customer relationships are amortized over their respective useful lives on an accelerated basis reflecting the period of expected derived benefits of the underlying assets. Developed technology consists of products that have reached technological feasibility and trade names represent acquired company and product names. To value the developed technology and trade name assets, the Company utilized a relief from royalty method. Under the methodology, fair value is calculated as the discounted cash flow savings accruing to the owner for not having to pay the royalty. Key assumptions included expected revenue attributable to the assets, royalty rates, discount rate and estimated asset lives. Customer relationships represent the underlying relationships with certain customers to provide ongoing services and continued product sale opportunities. The Company utilized excess earnings methodology to derive the fair value of the customer relationships. Key assumptions included expected attrition of customer’s rates, operating income margins and discount rate. The Company used a risk-adjusted discount rate of 14.4% in determining the fair value of the intangible assets.

The goodwill recorded as a result of the Aushon Acquisition represents the strategic benefits of growing the Company’s product portfolio and the expected revenue growth from increased market penetration from future products and customers. The goodwill was recorded as an asset (Note 14). None of the goodwill recorded is tax deductible for income tax purposes.

The Company incurred a total of $0.1 million in transaction costs in connection with the transaction, which were included in selling, general and administrative expense within the consolidated statement of operations for the twelve months ended December 31, 2018.

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets

Goodwill and Intangible Assets

14. Goodwill and Intangible Assets

As of December 31, 2018 the carrying amount of goodwill was $1.3 million. The following is a rollforward of our goodwill balance (in thousands):


	Goodwill
Balance as of December 31, 2017	$	—
Goodwill acquired		1,308
Balance as of December 31, 2018	$	1,308

Intangible assets consist of the following (dollars in thousands):


		December 31, 2018
	Estimated Useful	Gross Carrying		Accumulated				Weighted average
	Life (in years)	Value		Amortization		Net Carrying Value		life remaining
Developed technology	7	$	1,650	$	(378)	$	1,272	6.08
Customer relationships	10		1,250		(208)		1,042	9.08
Tradenames	3		50		(15)		35	2.08
Total		$	2,950	$	(601)	$	2,348

The Company recorded amortization expense of $0.6 million for the fiscal year ended December 31, 2018. No amortization expense was recognized in the fiscal year ended December 31, 2017 and 2016 as the intangible assets are a result of the purchase of Aushon BioSystems in January 2018. Amortization relating to developed technology is recorded within research and development expense, amortization of customer relationships is recorded within sales and marketing expenses, and amortization of tradenames is recorded within general and administrative expenses.

As of December 31, 2018, the Company expects to record the following amortization expense (amounts in thousands):


For the Years Ended December 31,	Estimated Amortization Expense
2019	$	582
2020		500
2021		403
2022		320
2023		238
2024 and thereafter		305

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Related party transactions	12 Months Ended
Related party transactions	Dec. 31, 2018
Related party transactions
Related party transactions	15. Related party transactions As described in Notes 11 and 7, bioMérieux is a customer through its Joint Development and License Agreement and also a holder of the Company’s common stock. bioMérieux formerly also had a designee on the Company’s Board of Directors. They Company recognized revenue related to the JDLA with bioMérieux of $2.1 million, $1.1 million, and $0.2 million, in the years ended December 31, 2018, 2017, and 2016 respectively, from bioMérieux. They also had no deferred revenue as of December 31, 2018 and had deferred revenue of $2.1 million at December 31, 2017. As described in Note 8, bioMérieux purchased shares of our Series C Preferred Stock totaling $7.0 million in the year ended December 31, 2015. As described in Note 7, in March 2016, the Company issued an aggregate of 12,420,262 shares of Series D Preferred Stock for an aggregate purchase price of $45.6 million. Of the amount issued, $22.9 million was purchased by the Company’s existing principal stockholders, officers and directors. As described in Note 7, in June 2017, the Company issued an aggregate of 2,113,902 share of Series D‑1 Preferred Stock for an aggregate purchase price of $8.5 million. Of the amount issued, $1.0 million was purchased by a director of the Company. As described in Note 9, in June 2007, the Company entered into a license agreement (the License Agreement) for certain intellectual property with Tufts University (Tufts). Tufts is a related party to the Company due to Tuft’s equity ownership in the Company and because a board member of the Company’s Board of Directors was affiliated with Tufts. During the years ended December 31, 2018, 2017, and 2016 the Company recorded royalty expense of $0.7 million, $0.5 million, and $0.3 million, respectively, in cost of product revenue on the consolidated statements of operations and comprehensive loss. During the year ended December 31, 2016, the Company recognized $0.4 million as cost of license revenue associated with a payment made to Tufts. During the year ended December 31, 2017 Harvard University became a related party. Revenue recorded from sales to Harvard University were less than $0.1 million for each of the years ended December 31, 2018 and December 31, 2017. On November 28th, the Company entered into a sponsor agreement with PPH, a 501(c)6 not-for-profit entity of which an executive of the Company is a board member, through December 31, 2018. The agreement commits a maximum of $120,000 in funds and services to be provided to PPH for the term of the agreement. The agreement is terminable by either party and does not bind the Company to beyond the term of the agreement. As of the year ended December 31, 2018, the Company had a total contributed amount less than $0.1 million.

Restricted Cash	12 Months Ended
Restricted Cash	Dec. 31, 2018
Restricted Cash
Restricted Cash	16. Restricted Cash The Company’s restricted cash consists of cash that the Company is contractually obligated to maintain in accordance the terms of the Letter of Credit in the lease agreement. The $1.0 million Letter of Credit drawable by the lessor under specifically outlined conditions within the lease, which are primarily related to rent payments. The amount of the Letter of Credit will be reduced at 41 and 65 months after the commencement date of the lease to $750,000 and then $250,000, respectively.

Quarterly Data (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Data (Unaudited)

Quarterly Data (Unaudited)

17. Quarterly Data (Unaudited)

(In thousands, except per share data)


2018	Q1		Q2		Q3		Q4		Total Year
Product revenue	$	4,745	$	5,200	$	5,962	$	7,458	$	23,365
Service and other revenue		2,507		3,174		3,017		3,419		12,117
Collaboration and license revenue		269		269		1,612		—		2,150
Total revenue		7,521		8,643		10,591		10,877		37,632
Operating expenses:
Cost of product revenue		2,773		2,945		3,277		3,734		12,729
Cost of services and other revenue		1,576		1,725		1,719		1,935		6,955
Research and development		3,644		3,705		4,411		4,045		15,805
Selling, general and administrative		6,691		7,579		8,846		10,577		33,693
Total operating expenses		14,684		15,954		18,253		20,291		69,182
Loss from operations		(7,163)		(7,311)		(7,662)		(9,414)		(31,550)
Interest expense, net		(24)		16		30		24		46
Other (expense) income, net		(15)		(48)		(25)		81		(7)
Tax expense		—		—		—		(25)		(25)
Net loss	$	(7,202)	$	(7,343)	$	(7,657)	$	(9,334)	$	(31,536)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss		(7,202)		(7,343)		(7,657)		(9,334)		(31,536)
Net loss attributable to common stockholders		(7,202)		(7,343)		(7,657)		(9,334)		(31,536)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.33)	$	(0.34)	$	(0.35)	$	(0.42)	$	(1.43)
Weighted-average common shares outstanding, basic and diluted		21,788,605		21,890,978		22,670,786		22,221,305		21,994,317


2017	Q1		Q2		Q3		Q4		Total Year
Product revenue	$	3,425	$	3,337	$	3,293	$	4,069	$	14,124
Service and other revenue		1,644		1,608		2,172		2,252		7,676
Collaboration and license revenue		269		268		269		268		1,074
Total revenue		5,338		5,213		5,734		6,589		22,874
Operating expenses:
Cost of product revenue		1,834		1,834		1,905		2,169		7,742
Cost of services and other revenue		1,144		1,198		1,264		1,539		5,145
Research and development		4,250		3,903		4,224		3,927		16,304
Selling, general and administrative		4,166		4,747		4,728		6,047		19,688
Total operating expenses		11,394		11,682		12,121		13,682		48,879
Loss from operations		(6,056)		(6,469)		(6,387)		(7,093)		(26,005)
Interest expense, net		(255)		(240)		(240)		(216)		(951)
Other (expense) income, net		(80)		77		13		(73)		(63)
Tax Expense		—		—		—		—		—
Net loss	$	(6,391)	$	(6,632)	$	(6,614)	$	(7,382)	$	(27,019)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss		(6,391)		(6,632)		(6,614)		(7,382)		(27,019)
Accretion of preferred stock to redemption value		(1,090)		(1,099)		(1,112)		(809)		(4,110)
Accrued dividends on preferred stock		(16)		(16)		(16)		(11)		(59)
Net loss attributable to common stockholders		(7,497)		(7,747)		(7,742)		(8,202)		(31,188)
Net loss per share attributable to common stockholders, basic and diluted	$	(3.18)	$	(3.21)	$	(3.13)	$	(1.06)	$	(8.30)
Weighted-average common shares outstanding, basic and diluted		2,357,503		2,416,984		2,475,166		7,731,514		3,756,954

Significant accounting policies (Policies)

12 Months Ended

Dec. 31, 2018

Significant accounting policies

Principles of consolidation

Use of estimates

Revenue recognition

Product revenue

Service and other revenue

Collaboration and license revenue

Multiple element arrangements

Distributor transactions

Business combinations

Restricted Cash

Cost of revenue

Cost of license revenue, related party consists of license fees that are the direct results of cash payments received related to license agreements.

Research and development expenses

Selling, general, and administrative expense

Net loss per share


	Year Ended December 31,
	2018	2017	2016
Series A redeemable convertible preferred stock	—	—	4,884,869
Series B redeemable convertible preferred stock	—	—	1,873,561
Series C redeemable convertible preferred stock	—	—	2,677,649
Series D redeemable convertible preferred stock	—	—	3,864,421
Unvested restricted common stock	361,468	177,192	376,248
Outstanding stock options	2,476,911	2,249,843	1,119,671
Outstanding preferred warrants	—	—	326,374
Outstanding common stock warrants	76,041	86,090	—
Total	2,914,420	2,513,125	15,122,793

Cash and Cash equivalents


	Year Ended December 31,
	2018		2017
Cash and Cash Equivalents
Cash	$	1,821	$	1,500
Money Market funds invested in U.S. Treasury obligations		42,608		78,182
Total cash and cash equivalents	$	44,429	$	79,682

Restricted cash and deposits

Accounts Receivable and allowance for doubtful accounts

Inventory

Property and equipment


Laboratory and manufacturing equipment		Five years
Computers and software		Three years
Office furniture and equipment		Seven years
Leasehold improvements		Shorter of the useful life of the asset or the remaining term of the lease

Software development costs

Investments

Fair value of financial instruments

Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities.

Level 2 inputs are inputs other than quoted prices that are observable for the asset or liability, either directly or indirectly; and

Level 3 inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability.

Fair value measurements as of December 31, 2018 are as follows (in thousands):


			Quoted		Significant
			prices		other		Significant
			in active		observable		unobservable
			markets		inputs		inputs
Description	Total		(Level 1)		(Level 2)		(Level 3)

Financial Assets
Cash Equivalents	$	42,608	$	42,608		—	$	—
Note receivable		150		—		—		150
Total	$	42,758	$	42,608		—	$	150

Fair value measurements as of December 31, 2017 are as follows (in thousands):

Quoted

Significant

prices

other

Significant

in active

observable

unobservable

markets

inputs

Description

Total

(Level 1)

(Level 2)

(Level 3)

Financial Assets

Cash Equivalents

78,182

—

Total

78,182

—

On January 29, 2016, the Company issued a warrant to purchase 57,810 shares of Series C Preferred Stock to a lender related to a second amendment to a debt facility (Note 8)

On November 18, 2016, the Company issued a warrant to purchase 700,000 shares of Series A‑3 Preferred Stock to a vendor (Note 7).

The changes in preferred stock warrant liability measured at fair value for which the Company has used Level 3 inputs to determine fair value are as follows (in thousands):


	Warrant
	liability
Balance at December 31, 2015	$	5,547
Issuance of warrants related to debt facility		128
Issuance of warrants related to a vendor		2,078
Changes in fair value of warrants		307
Warrant exercises		(5,258)
Balance at December 31, 2016		2,802
Issuance of warrants related to debt facility		119
Changes in fair value of warrants		90
Warrant exercises		(2,188)
Conversion to warrants to purchase common stock in connection with IPO		(823)
Balance at December 31, 2017	$	—

Value of

underlying

Probability

Series D

Series C

Series B

Series A‑3

Series A‑2

of an initial

preferred

public

Balance sheet date

stock

Volatility

offering

December 7, 2017

4.67

N/A

4.67

100

Warranties

Income taxes

Credit, product and supplier concentrations and off-balance-sheet risk

Customers outside the United States represented 40% and 34% of the Company’s gross trade accounts receivable balance as of December 31, 2018 and 2017 respectively.

Segment information

Net revenue by product and service line are as follows (in thousands):


	Year ended December 31,
	2018		2017		2016
Product revenue	$	23,365	$	14,124	$	10,601
Service and other revenue		12,117		7,676		5,012
Collaboration and license revenue		2,150		1,074		1,972
Total revenue	$	37,632	$	22,874	$	17,585


	Year ended December 31,
	2018				2017				2016
North America	$	22,706	60	%	$	13,864	61	%	$	13,018	74	%
EMEA		11,742	31	%		6,922	30	%		3,416	19	%
Asia Pacific		3,184	8	%		2,088	9	%		1,151	7	%
Total	$	37,632	100	%	$	22,874	100	%	$	17,585	100	%

Stock-based compensation


	Year Ended December 31,
	2018		2017		2016
Risk-free interest rate	2.6% - 3.0	%	1.8% - 2.1	%	1.2% - 1.3	%
Expected dividend yield	None		None		None
Expected term (in years)	5.9		6.0		6.0
Expected volatility	32.4% - 36.8	%	46.0% - 52.0	%	44.9% - 49.0	%

Recent accounting pronouncements

Significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2018

Significant accounting policies

Schedule of outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share


	Year Ended December 31,
	2018	2017	2016
Series A redeemable convertible preferred stock	—	—	4,884,869
Series B redeemable convertible preferred stock	—	—	1,873,561
Series C redeemable convertible preferred stock	—	—	2,677,649
Series D redeemable convertible preferred stock	—	—	3,864,421
Unvested restricted common stock	361,468	177,192	376,248
Outstanding stock options	2,476,911	2,249,843	1,119,671
Outstanding preferred warrants	—	—	326,374
Outstanding common stock warrants	76,041	86,090	—
Total	2,914,420	2,513,125	15,122,793

Schedule of cash and cash equivalents

are carried at fair value based on quoted prices for identical assets. Cash and cash equivalents consists of the following (in thousands):


	Year Ended December 31,
	2018		2017
Cash and Cash Equivalents
Cash	$	1,821	$	1,500
Money Market funds invested in U.S. Treasury obligations		42,608		78,182
Total cash and cash equivalents	$	44,429	$	79,682

Schedule of estimated useful lives


Laboratory and manufacturing equipment		Five years
Computers and software		Three years
Office furniture and equipment		Seven years
Leasehold improvements		Shorter of the useful life of the asset or the remaining term of the lease

Schedule of fair value measurements

Fair value measurements as of December 31, 2018 are as follows (in thousands):


			Quoted		Significant
			prices		other		Significant
			in active		observable		unobservable
			markets		inputs		inputs
Description	Total		(Level 1)		(Level 2)		(Level 3)

Financial Assets
Cash Equivalents	$	42,608	$	42,608		—	$	—
Note receivable		150		—		—		150
Total	$	42,758	$	42,608		—	$	150

Fair value measurements as of December 31, 2017 are as follows (in thousands):

Quoted

Significant

prices

other

Significant

in active

observable

unobservable

markets

inputs

Description

Total

(Level 1)

(Level 2)

(Level 3)

Financial Assets

Cash Equivalents

78,182

—

Total

78,182

—

Schedule of changes in preferred stock warrant liability measured at fair value

The changes in preferred stock warrant liability measured at fair value for which the Company has used Level 3 inputs to determine fair value are as follows (in thousands):


	Warrant
	liability
Balance at December 31, 2015	$	5,547
Issuance of warrants related to debt facility		128
Issuance of warrants related to a vendor		2,078
Changes in fair value of warrants		307
Warrant exercises		(5,258)
Balance at December 31, 2016		2,802
Issuance of warrants related to debt facility		119
Changes in fair value of warrants		90
Warrant exercises		(2,188)
Conversion to warrants to purchase common stock in connection with IPO		(823)
Balance at December 31, 2017	$	—

Schedule of assumptions were utilized to determine the fair value of each warrant to purchase preferred stock

Value of

underlying

Probability

Series D

Series C

Series B

Series A‑3

Series A‑2

of an initial

preferred

public

Balance sheet date

stock

Volatility

offering

December 7, 2017

4.67

N/A

4.67

100

Schedule of net revenue by product and service line

Net revenue by product and service line are as follows (in thousands):


	Year ended December 31,
	2018		2017		2016
Product revenue	$	23,365	$	14,124	$	10,601
Service and other revenue		12,117		7,676		5,012
Collaboration and license revenue		2,150		1,074		1,972
Total revenue	$	37,632	$	22,874	$	17,585

Schedule of total revenue by geography and as a percentage of total revenue


	Year ended December 31,
	2018				2017				2016
North America	$	22,706	60	%	$	13,864	61	%	$	13,018	74	%
EMEA		11,742	31	%		6,922	30	%		3,416	19	%
Asia Pacific		3,184	8	%		2,088	9	%		1,151	7	%
Total	$	37,632	100	%	$	22,874	100	%	$	17,585	100	%

Summary of fair value assumptions of stock options granted to employees and directors for their services on the Company's Board of Directors


	Year Ended December 31,
	2018		2017		2016
Risk-free interest rate	2.6% - 3.0	%	1.8% - 2.1	%	1.2% - 1.3	%
Expected dividend yield	None		None		None
Expected term (in years)	5.9		6.0		6.0
Expected volatility	32.4% - 36.8	%	46.0% - 52.0	%	44.9% - 49.0	%

Inventory (Tables)

12 Months Ended

Dec. 31, 2018

Inventory

Summary of inventory

Inventory consists of the following (in thousands):


	As of
	December 31,
	2018		2017
Raw materials	$	1,546	$	1,032
Work in process		2,331		968
Finished goods		2,068		1,571
Total	$	5,945	$	3,571

Property and equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property and equipment

Schedule of Property and equipment

Property and equipment consists of the following (in thousands):


	As of
	December 31,
	2018		2017
Laboratory and manufacturing equipment	$	4,127	$	2,969
Office furniture and equipment		789		689
Computers and software		786		459
Leasehold improvements		244		180
		5,946		4,297
Less: accumulated depreciation		(3,023)		(2,423)
Total	$	2,923	$	1,874

Other accrued expenses (Tables)

12 Months Ended

Dec. 31, 2018

Other accrued expenses

Summary of other accrued expenses

Other accrued expenses consist of the following (in thousands):


	As of December 31,
	2018		2017
Accrued inventory	$	599	$	835
Accrued royalties		323		221
Accrued professional services		723		346
Accrued development costs		795		1,559
Accrued other		689		599
Total accrued expenses	$	3,129	$	3,560

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Taxes

Schedule of components of income (loss) before income taxes


	Year Ended December 31,
	2018		2017		2016
United States	$	(31,436)	$	(27,019)	$	(23,173)
Foreign		(75)		—		—
	$	(31,511)	$	(27,019)	$	(23,173)

Schedule of provision for (benefit from) income taxes


	Year Ended December 31,
	2018		2017		2016
Current:
United States
Federal	$	—	$	—	$	—
State		18		—		—
Foreign		—		—		—
Total current income tax provision		18		—		—
Deferred
United States
Federal		2		—		—
State		5		—		—
Foreign		—		—		—
Total deferred income tax provision (benefit)		7		—		—
Total income tax provision (benefit)	$	25	$	—	$	—

Schedule of reconciliation of the federal statutory income tax rate to the effective tax rate

A reconciliation of the federal statutory income tax rate to the effective tax rate is as follows:


	Year Ended December 31,
	2018		2017
Federal statutory income tax rate	21.0	%	34.0	%
State taxes, net of federal tax benefit	6.0	%	4.8	%
Stock compensation	1.1	%	0.0	%
Permanent items	(1.2)	%	(1.6)	%
Tax Credits	2.7	%	2.6	%
Foreign differential	0.0	%	0.0	%
U.S. Tax Reform	0.0	%	(53.2)	%
Other, net	0.2	%	(1.1)	%
Valuation Allowance	(29.9)	%	14.5	%
Effective income tax rate	(0.1)	%	0.0	%

Schedule of deferred tax assets and liabilities


	December 31,
	2018		2017
Deferred tax assets:
Net operating loss carryforwards	$	35,623	$	27,952
Research and development credits		4,678		3,637
Deferred revenue		1,614		1,795
Depreciation		86		629
Amortization		792		—
Stock compensation		541		185
Other deferred tax assets		1,378		614
Total deferred tax assets		44,712		34,812
Valuation allowance		(44,033)		(34,552)
Subtotal		679		260
Section 481(a) Adjustment - Accrued Bonus		(59)		(118)
Amortization		(610)		—
Goodwill		(17)
Stock-based compensation		—		(142)
Net deferred tax assets (liability)	$	(7)	$	—

Redeemable convertible preferred stock (Tables)

12 Months Ended

Dec. 31, 2018

Redeemable convertible preferred stock

Schedule of redeemable convertible preferred stock


		Shares of
		Preferred
Preferred Stock		Stock
A‑1		3,972,415
A‑2		10,427,586
A‑3		2,000,000
B		6,021,636
C		8,092,895
C‑1		544,332
D		12,420,262
D‑1		2,113,902
Total		45,593,028

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units (Tables)

12 Months Ended

Dec. 31, 2018

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units

Schedule of common stock reserved


	Year ended December 31,
	2018	2017
Common stock warrants	76,041	86,090
Common stock options and unvested restricted common stock	2,838,402	2,427,035
Shares reserved for future awards under compensation plan	2,433,999	3,500,620
	5,348,442	6,013,745

Summary of warrant activity


		Weighted
	Issued and	Average
	exercisable	Exercise Price
As of December 31, 2017	86,090	$	9.14
Issued	10,000		4.83
Exercised	(16,718)		11.73
Cancelled	(3,331)	$	11.73
As of December 31, 2018	76,041		10.10

Summary of share-based compensation expense for all stock awards


	Year ended December 31,
	2018		2017		2016
Cost of product revenue	$	55	$	24	$	6
Cost of service and other revenue		173		52		12
Research and development		513		180		59
General and administrative		4,143		1,912		851
Total	$	4,884	$	2,168	$	928

Summary of stock option activity


		Weighted-		Remaining	Aggregate
		average		contractual	intrinsic
		exercise		life	value
	Options	price		(in years)	(in thousands)
Outstanding at December 31, 2016	1,119,671	$	2.99	6.8		5,796
Granted	1,281,135	$	8.46
Exercised	(90,265)	$	2.25
Cancelled or forfeited	(60,698)	$	6.16
Outstanding at December 31, 2017	2,249,843	$	6.05	7.8		34,695
Granted	729,224	$	18.36
Exercised	(407,901)	$	4.57
Cancelled or forfeited	(94,255)	$	13.16
Outstanding at December 31, 2018	2,476,911	$	9.65	7.733	$	22,108
Vested and expected to vest at December 31, 2018	2,476,911	$	9.65	7.733	$	22,108
Exercisable at December 31, 2018	1,143,480	$	5.68	6.514	$	14,440

Summary of restricted stock activity


		Weighted-average
		grant date
		fair value
	Shares	per share
Unvested restricted common stock as of December 31, 2015	623,869	3.12
Vested	(247,621)	3.09
Unvested restricted common stock as of December 31, 2016	376,248	3.12
Vested	(199,056)	3.12
Unvested restricted common stock as of December 31, 2017	177,192	3.11
Vested	(137,386)	3.11
Unvested restricted common stock as of December 31, 2018	39,806	3.12

Summary of restricted stock units activity


		Weighted-average
		grant date
		fair value
	Shares	per share
Unvested restricted stock units as of December 31, 2017	—
Granted	422,027	$	15.65
Vested	(99,990)	$	15.02
Cancelled or Forfeited	(375)	$	18.40
Unvested restricted stock units as of December 31, 2018	321,662	$	15.84

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details

Commitments and contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments and contingencies

Schedule of minimum future rent payments under the lease agreement

As of December 31, 2018, the minimum future rent payments under the lease agreements are as follows (in thousands):


Years ending December 31:
2019	$	1,172
2020		2,013
2021		3,290
2022		3,372
2023 and Forward		29,207
	$	39,054

Long Term Debt (Tables)

12 Months Ended

Dec. 31, 2018

Long Term Debt

Schedule of debt payment obligations due based on principal payments

Debt payment obligations due based on principal payments are as follows (in thousands):


Years ending December 31:
2019	$	0
2020		7,763
	$	7,763

Business combinations (Tables)

12 Months Ended

Dec. 31, 2018

Business combinations

Schedule of fair value of assets acquired and liabilities assumed

The following table presents the allocation of the purchase consideration for the transaction as of January 30, 2018 including the allocation of the purchase consideration (in thousands):


Fair value of consideration transferred:
Cash	$	3,200
Obligation to issue cash		800
Total acquisition consideration	$	4,000

Fair value of assets acquired and liabilities assumed:
Cash and cash equivalents	$	199
Accounts receivable		210
Inventory		828
Prepaid expenses		71
Property and equipment and other non-current assets		180
Intangible Assets		2,950
Goodwill		1,308
Total assets acquired		5,746
Contractual obligations		(1,155)
Accounts payable and accrued liabilities		(591)
Net assets acquired	$	4,000

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets

Rollforward of goodwill balance

The following is a rollforward of our goodwill balance (in thousands):


	Goodwill
Balance as of December 31, 2017	$	—
Goodwill acquired		1,308
Balance as of December 31, 2018	$	1,308

Summary of intangible assets

Intangible assets consist of the following (dollars in thousands):


		December 31, 2018
	Estimated Useful	Gross Carrying		Accumulated				Weighted average
	Life (in years)	Value		Amortization		Net Carrying Value		life remaining
Developed technology	7	$	1,650	$	(378)	$	1,272	6.08
Customer relationships	10		1,250		(208)		1,042	9.08
Tradenames	3		50		(15)		35	2.08
Total		$	2,950	$	(601)	$	2,348

Schedule of future estimated amortization expense of acquired intangibles

As of December 31, 2018, the Company expects to record the following amortization expense (amounts in thousands):


For the Years Ended December 31,	Estimated Amortization Expense
2019	$	582
2020		500
2021		403
2022		320
2023		238
2024 and thereafter		305

Quarterly Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Data (Unaudited)

Quarterly Data (Unaudited)

(In thousands, except per share data)


2018	Q1		Q2		Q3		Q4		Total Year
Product revenue	$	4,745	$	5,200	$	5,962	$	7,458	$	23,365
Service and other revenue		2,507		3,174		3,017		3,419		12,117
Collaboration and license revenue		269		269		1,612		—		2,150
Total revenue		7,521		8,643		10,591		10,877		37,632
Operating expenses:
Cost of product revenue		2,773		2,945		3,277		3,734		12,729
Cost of services and other revenue		1,576		1,725		1,719		1,935		6,955
Research and development		3,644		3,705		4,411		4,045		15,805
Selling, general and administrative		6,691		7,579		8,846		10,577		33,693
Total operating expenses		14,684		15,954		18,253		20,291		69,182
Loss from operations		(7,163)		(7,311)		(7,662)		(9,414)		(31,550)
Interest expense, net		(24)		16		30		24		46
Other (expense) income, net		(15)		(48)		(25)		81		(7)
Tax expense		—		—		—		(25)		(25)
Net loss	$	(7,202)	$	(7,343)	$	(7,657)	$	(9,334)	$	(31,536)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss		(7,202)		(7,343)		(7,657)		(9,334)		(31,536)
Net loss attributable to common stockholders		(7,202)		(7,343)		(7,657)		(9,334)		(31,536)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.33)	$	(0.34)	$	(0.35)	$	(0.42)	$	(1.43)
Weighted-average common shares outstanding, basic and diluted		21,788,605		21,890,978		22,670,786		22,221,305		21,994,317


2017	Q1		Q2		Q3		Q4		Total Year
Product revenue	$	3,425	$	3,337	$	3,293	$	4,069	$	14,124
Service and other revenue		1,644		1,608		2,172		2,252		7,676
Collaboration and license revenue		269		268		269		268		1,074
Total revenue		5,338		5,213		5,734		6,589		22,874
Operating expenses:
Cost of product revenue		1,834		1,834		1,905		2,169		7,742
Cost of services and other revenue		1,144		1,198		1,264		1,539		5,145
Research and development		4,250		3,903		4,224		3,927		16,304
Selling, general and administrative		4,166		4,747		4,728		6,047		19,688
Total operating expenses		11,394		11,682		12,121		13,682		48,879
Loss from operations		(6,056)		(6,469)		(6,387)		(7,093)		(26,005)
Interest expense, net		(255)		(240)		(240)		(216)		(951)
Other (expense) income, net		(80)		77		13		(73)		(63)
Tax Expense		—		—		—		—		—
Net loss	$	(6,391)	$	(6,632)	$	(6,614)	$	(7,382)	$	(27,019)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss		(6,391)		(6,632)		(6,614)		(7,382)		(27,019)
Accretion of preferred stock to redemption value		(1,090)		(1,099)		(1,112)		(809)		(4,110)
Accrued dividends on preferred stock		(16)		(16)		(16)		(11)		(59)
Net loss attributable to common stockholders		(7,497)		(7,747)		(7,742)		(8,202)		(31,188)
Net loss per share attributable to common stockholders, basic and diluted	$	(3.18)	$	(3.21)	$	(3.13)	$	(1.06)	$	(8.30)
Weighted-average common shares outstanding, basic and diluted		2,357,503		2,416,984		2,475,166		7,731,514		3,756,954

Organization and operations (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 07, 2017	Dec. 04, 2017	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) shares	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) $ / shares shares	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($)
Initial Public Offering
Common stock authorized (in shares)			120,000,000	120,000,000				120,000,000				120,000,000	120,000,000
Accumulated deficit \| $			$ (144,352)	$ (175,888)				$ (144,352)				$ (175,888)	$ (144,352)
Net loss \| $				(9,334)	$ (7,657)	$ (7,343)	$ (7,202)	(7,382)	$ (6,614)	$ (6,632)	$ (6,391)	(31,536)	(27,019)	$ (23,173)
Unrestricted cash and cash equivalents \| $			$ 79,682	$ 44,429				79,682				$ 44,429	$ 79,682
Reverse stock split ratio		0.311
Common stock
Initial Public Offering
Issuance of stock, net of issuance costs (in shares)													4,916,480
Conversion of preferred stock to common stock (in shares)													14,185,744
Reverse stock split ratio		0.311										3.214
Initial Public Offering
Initial Public Offering
Conversion of preferred stock to common stock (in shares)			14,185,744
Carrying value of preferred stock, notes and warrants reclassified as common stock and additional paid-in capital \| $			$ 143,300					$ 143,300					$ 143,300
Common stock authorized (in shares)			120,000,000					120,000,000					120,000,000
Preferred stock authorized (in shares)			5,000,000					5,000,000					5,000,000
Initial Public Offering \| Common stock
Initial Public Offering
Issuance of stock, net of issuance costs (in shares)			4,916,480
Shares issued (in dollars per share) \| $ / shares			$ 15.00					$ 15.00					$ 15.00
Aggregate net proceeds from IPO \| $			$ 65,600
Reverse stock split ratio	3.214

Significant accounting policies - Use of estimates (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Revenue recognition
Number of bi-annual preventative maintenance visits included in implied warranty and extended service contracts	2
Term of average selling prices used to determine estimate of current sales price	12 months
Instrument and accessories
Revenue recognition
Standard warranty period	1 year
Implied warranty period	1 year
Collaboration and license revenue
Revenue recognition
Related party revenue	$ 2,150	$ 1,074	$ 172

Significant accounting policies - Net loss per share (Details)		12 Months Ended
	Dec. 04, 2017	Dec. 31, 2018 shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share		2,914,420	2,513,125	15,122,793
Reverse stock split ratio	0.311
Series A Preferred Stock
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share				4,884,869
Series B Preferred Stock
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share				1,873,561
Series C Preferred Stock
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share				2,677,649
Series D Preferred Stock
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share				3,864,421
Unvested restricted common stock
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share		361,468	177,192	376,248
Outstanding stock options
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share		2,476,911	2,249,843	1,119,671
Outstanding preferred warrants
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share				326,374
Outstanding warrants
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Number of dilutive securities excluded in the calculation of diluted net loss per share		76,041	86,090
Common stock
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Obligation to issue warrants, in shares		93,341
Series A-3 Preferred Stock
Outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share
Obligation to issue warrants, in shares			300,000	300,000

Significant accounting policies - Cash and Cash equivalents and Restricted cash and deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash equivalents
Cash	$ 1,821	$ 1,500
Money Market funds invested in U.S. Treasury obligations	42,608	78,182
Total cash and cash equivalents	44,429	79,682
Restricted cash and deposits
Restricted cash and deposits	1,400	$ 400
Restricted Cash	1,000
Other current and noncurrent assets
Restricted cash and deposits
Restricted cash and deposits	$ 400

Significant accounting policies - Property and equipment (Details)	12 Months Ended
	Dec. 31, 2018
Laboratory and manufacturing equipment
Property and equipment
Estimated useful life (in years)	5 years
Computers and software
Property and equipment
Estimated useful life (in years)	3 years
Office furniture and equipment
Property and equipment
Estimated useful life (in years)	7 years

Significant accounting policies - Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2016
Investments
Impairment on investments	$ 0.0	$ 0.0	$ 0.0
Minority interest in preferred stock in privately held company
Investments
Purchase price of investment					$ 0.3
Investment in a convertible notes of a privately held company
Investments
Investment principle amount				$ 0.2

Significant accounting policies - Fair value of financial instruments (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Dec. 07, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Nov. 30, 2017	Mar. 31, 2017	Jan. 31, 2017	Nov. 18, 2016	Jul. 31, 2016	Feb. 29, 2016	Jan. 29, 2016	Jan. 01, 2016
Fair value of financial instruments
Cash equivalents		$ 78,182		$ 42,608
Note receivable				150
Total		$ 78,182		42,758
Assumptions to Determine the Fair Value
Probability of an Initial Public Offering			40.00%
Initial Public Offering
Assumptions to Determine the Fair Value
Volatility (in percentage)	46.00%
Probability of an Initial Public Offering	100.00%
Series A-2 Preferred Stock
Fair value of financial instruments
Warrants to purchase shares												64,441
Series A-2 Preferred Stock \| Initial Public Offering
Assumptions to Determine the Fair Value
Value of underlying liability	$ 4.67
Series A-3 Preferred Stock
Fair value of financial instruments
Warrants to purchase shares		700,000					700,000	700,000		1,300,000		1,300,000
Series A-3 Preferred Stock \| Initial Public Offering
Assumptions to Determine the Fair Value
Value of underlying liability	4.67
Series B Preferred Stock
Fair value of financial instruments
Warrants to purchase shares									397,530			562,488
Series C Preferred Stock
Fair value of financial instruments
Warrants to purchase shares		111,114			31,283						57,810	226,733
Series C Preferred Stock \| Initial Public Offering
Assumptions to Determine the Fair Value
Value of underlying liability	4.67
Series D Preferred Stock
Fair value of financial instruments
Warrants to purchase shares						38,828
Series D Preferred Stock \| Initial Public Offering
Assumptions to Determine the Fair Value
Value of underlying liability	$ 4.67
Level 1
Fair value of financial instruments
Cash equivalents		$ 78,182		42,608
Total		78,182		42,608
Level 3
Fair value of financial instruments
Note receivable				150
Total				$ 150
Changes in preferred stock warrant liability measured at fair value
Balance at beginning		2,802	$ 5,547
Changes in fair value of warrants		90	307
Warrant exercise		(2,188)	(5,258)
Conversion to warrants to purchase common stock in connection with IPO		(823)
Balance at ending			2,802
Level 3 \| Debt facility
Changes in preferred stock warrant liability measured at fair value
Issuance of warrants		$ 119	128
Level 3 \| Vendor
Changes in preferred stock warrant liability measured at fair value
Issuance of warrants			$ 2,078

Significant accounting policies - Warranties (Details)	12 Months Ended
Significant accounting policies - Warranties (Details)	Dec. 31, 2018
Significant accounting policies
Warranty period (in years)	1 year

Significant accounting policies - Credit, product and supplier concentrations and off-balance-sheet risk (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk
Concentration risk (in percent)	100.00%	100.00%	100.00%
Accounts Receivable Concentration \| Customers outside the United States
Concentration Risk
Concentration risk (in percent)	40.00%	34.00%
Accounts Receivable Concentration \| One customer
Concentration Risk
Concentration risk (in percent)		16.00%	26.00%
Revenue Concentration \| One customer
Concentration Risk
Concentration risk (in percent)			11.00%

Significant accounting policies - Segment information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Total revenue	$ 10,877	$ 10,591	$ 8,643	$ 7,521	$ 6,589	$ 5,734	$ 5,213	$ 5,338	$ 37,632	$ 22,874	$ 17,585
Revenue by region as a percentage of total revenue									100.00%	100.00%	100.00%
North America
Disaggregation of Revenue [Line Items]
Total revenue									$ 22,706	$ 13,864	$ 13,018
Revenue by region as a percentage of total revenue									60.00%	61.00%	74.00%
EMEA
Disaggregation of Revenue [Line Items]
Total revenue									$ 11,742	$ 6,922	$ 3,416
Revenue by region as a percentage of total revenue									31.00%	30.00%	19.00%
Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenue									$ 3,184	$ 2,088	$ 1,151
Revenue by region as a percentage of total revenue									8.00%	9.00%	7.00%
Product revenue
Disaggregation of Revenue [Line Items]
Total revenue	7,458	5,962	5,200	4,745	4,069	3,293	3,337	3,425	$ 23,365	$ 14,124	$ 10,601
Service and other revenue
Disaggregation of Revenue [Line Items]
Total revenue	$ 3,419	3,017	3,174	2,507	2,252	2,172	1,608	1,644	12,117	7,676	5,012
Collaboration and license revenue
Disaggregation of Revenue [Line Items]
Total revenue		$ 1,612	$ 269	$ 269	$ 268	$ 269	$ 268	$ 269	$ 2,150	$ 1,074	$ 1,972

Significant accounting policies - Stock-based compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2017
New Accounting Pronouncement, Early Adoption
Expected dividend yield	0.00%	0.00%	0.00%
Expected term (in years)	5 years 10 months 24 days	6 years	6 years
Weighted-average fair value of options granted	$ 7.19	$ 4.52	$ 2.41
Probability of initial public offering			40.00%
Accumulated deficit	$ (175,888)	$ (144,352)
Minimum
New Accounting Pronouncement, Early Adoption
Risk-free interest rate	2.60%	1.80%	1.20%
Expected volatility	32.40%	46.00%	44.90%
Maximum
New Accounting Pronouncement, Early Adoption
Risk-free interest rate	3.00%	2.10%	1.30%
Expected volatility	36.80%	52.00%	49.00%
ASU No.2016-09 \| Restatement Adjustment
New Accounting Pronouncement, Early Adoption
Accumulated deficit				$ 100

Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory
Raw materials	$ 1,546	$ 1,032
Work in process	2,331	968
Finished goods	2,068	1,571
Total	$ 5,945	$ 3,571

Property and equipment (Details) $ in Thousands	12 Months Ended
Property and equipment (Details) $ in Thousands	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Property and equipment
Property and equipment, gross	$ 5,946	$ 4,297
Less: accumulated depreciation	(3,023)	(2,423)
Total	2,923	1,874
Depreciation expense	700	500
Laboratory and manufacturing equipment
Property and equipment
Property and equipment, gross	4,127	2,969
Laboratory and manufacturing instruments used internally
Property and equipment
Property and equipment, gross	1,400
Less: accumulated depreciation	$ (700)
Number of instruments used \| item	27
Office furniture and equipment
Property and equipment
Property and equipment, gross	$ 789	689
Computers and software
Property and equipment
Property and equipment, gross	786	459
Leasehold improvements
Property and equipment
Property and equipment, gross	$ 244	$ 180

Other accrued expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other accrued expenses
Accrued inventory	$ 599	$ 835
Accrued royalties	323	221
Accrued professional services	723	346
Accrued development costs	795	1,559
Accrued other	689	599
Total accrued expenses	$ 3,129	$ 3,560

Income Taxes - Components of income (loss) before income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of income (loss) before income taxes
United States	$ (31,436)	$ (27,019)	$ (23,173)
Foreign	(75)
Loss before income taxes	$ (31,511)	$ (27,019)	$ (23,173)

Income Taxes - Provision for (benefit from) income taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Provision for (benefit from) income taxes
Income tax benefit on net losses and tax credits		$ 0	$ 0	$ 0
Current:
State		18
Total current income tax provision		18
Deferred
Federal		2
State		5
Total deferred income tax provision (benefit)		7
Total income tax provision (benefit)	$ 25	$ 25

Income Taxes - Reconciliation of the federal statutory income tax rate to the effective tax rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes
Federal corporate income tax rate	21.00%	35.00%	35.00%
Reconciliation of the federal statutory income tax rate to the effective tax rate
Federal statutory income tax rate (in percent)	21.00%	34.00%
State taxes, net of federal tax benefit (in percent)	6.00%	4.80%
Stock compensation (in percent)	1.10%	0.00%
Permanent items (in percent)	(1.20%)	(1.60%)
Tax Credits (in percent)	2.70%	2.60%
Foreign differential (in percent)	0.00%	0.00%
U.S. Tax Reform (in percent)	0.00%	(53.20%)
Other, net (in percent)	0.20%	(1.10%)
Valuation Allowance (in percent)	(29.90%)	14.50%
Effective income tax rate (in percent)	(0.10%)	0.00%
Aushon acquisition
Income Taxes
Amortizable goodwill	$ 0.4

Income Taxes - Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 35,623	$ 27,952
Research and development credits	4,678	3,637
Deferred revenue	1,614	1,795
Depreciation	86	629
Amortization	792
Stock compensation	541	185
Other deferred tax assets	1,378	614
Total deferred tax assets	44,712	34,812
Valuation allowance	(44,033)	(34,552)
Subtotal	679	260
Section 481(a) Adjustment - Accrued Bonus	(59)	(118)
Depreciation	(610)
Goodwill	(17)
Stock-based compensation		$ (142)
Net deferred tax assets (liability)	$ (7)

Income taxes - Other (Details) - USD ($) $ in Thousands	12 Months Ended
Income taxes - Other (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes
Increase (decrease) in Valuation allowance	$ 9,400	$ (3,900)
Unrecognized tax benefit	0
Accrued interest or penalties	0	$ 0	$ 0
Federal
Income Taxes
Net operating loss (NOL) carryforwards	136,800
Tax credit carryforwards	3,800
State
Income Taxes
Net operating loss (NOL) carryforwards	108,800
Tax credit carryforwards	1,200
Foreign
Income Taxes
Net operating loss (NOL) carryforwards	75
Aushon acquisition
Income Taxes
Net operating loss (NOL) carryforwards	$ 900

Redeemable convertible preferred stock (Details) $ / shares in Units, $ in Millions					1 Months Ended							2 Months Ended	12 Months Ended
	Dec. 07, 2017 shares	Dec. 04, 2017	Dec. 31, 2015	Nov. 30, 2015	Nov. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares shares	Jan. 31, 2017 USD ($) $ / shares shares	Mar. 31, 2016 USD ($) $ / shares shares	Feb. 29, 2016 USD ($) $ / shares shares	May 31, 2015 USD ($) $ / shares shares	Jan. 31, 2015 USD ($) $ / shares shares	Jul. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 shares	Mar. 31, 2017 shares	Nov. 18, 2016 shares	Jan. 29, 2016 shares	Jan. 01, 2016 shares
Redeemable convertible preferred stock prior to IPO
Preferred stock, par value (in dollars per share) \| $ / shares													$ 0.001
Preferred stock conversion ratio		0.311
Conversion shares of common stock	45,593,028
Common stock
Redeemable convertible preferred stock prior to IPO
Preferred stock conversion ratio		0.311											3.214
Initial Public Offering
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares														5,000,000
Initial Public Offering \| Common stock
Redeemable convertible preferred stock prior to IPO
Preferred stock conversion ratio	3.214
Minimum percentage of outstanding shares to be converted													60.00%
Conversion shares of common stock	14,185,744
Initial Public Offering \| Common stock \| Minimum
Redeemable convertible preferred stock prior to IPO
Purchase price \| $ / shares													$ 5.00
Conversion, threshold gross proceeds \| $													$ 40.0
Stock Purchase Agreement \| bioMerieux
Redeemable convertible preferred stock prior to IPO
Milestone Amount \| $													10.0
Number of instalments			3	1
Milestone Payment1 \| bioMerieux
Redeemable convertible preferred stock prior to IPO
Milestone Amount \| $													5.0
Milestone Payment2 \| bioMerieux
Redeemable convertible preferred stock prior to IPO
Milestone Amount \| $													3.0
Milestone Payment3 \| bioMerieux
Redeemable convertible preferred stock prior to IPO
Milestone Amount \| $													$ 2.0
Preferred stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													47,015,449
Series A Preferred Stock
Redeemable convertible preferred stock prior to IPO
Fair value of preferred warrants \| $							$ 2.1		$ 3.9
Number of annual instalments													3
Series A-1 Preferred Stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													3,972,415
Annual rate on cumulative dividends \| $ / shares													$ 0.08
Cumulative accrued dividends \| $													$ 3.3
Liquidation preference per share \| $ / shares													$ 1.0416667
Votes per share													1
Eligibility to elect number of directors													3
Number of annual instalments													3
Conversion shares of common stock	3,972,415
Series A-2 Preferred Stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													10,492,027
Warrants to purchase shares																		64,441
Annual rate on cumulative dividends \| $ / shares													$ 0.08
Cumulative accrued dividends \| $													$ 7.8
Liquidation preference per share \| $ / shares													$ 1.0416667
Votes per share													1
Eligibility to elect number of directors													3
Number of annual instalments													3
Conversion shares of common stock	10,427,586
Series A-3 Preferred Stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													2,000,000
Warrants to purchase shares							700,000		1,300,000					700,000		700,000		1,300,000
Purchase price \| $ / shares							$ 0.001		$ 0.001
Liquidation preference per share \| $ / shares													$ 2.00
Votes per share													1
Number of annual instalments													3
Conversion shares of common stock	2,000,000
Series B Preferred Stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													6,186,594
Warrants to purchase shares												397,530						562,488
Warrants to purchase shares in cashless												76,700
Fair value of preferred warrants \| $												$ 1.4
Annual rate on cumulative dividends \| $ / shares													$ 0.16
Cumulative accrued dividends \| $													$ 5.7
Liquidation preference per share \| $ / shares													$ 2.00
Votes per share													1
Eligibility to elect number of directors													3
Number of annual instalments													3
Conversion shares of common stock	6,021,636
Series B Preferred Stock, purchase price $0.001 per share
Redeemable convertible preferred stock prior to IPO
Warrants to purchase shares												312,500
Purchase price \| $ / shares												$ 0.001
Series B Preferred Stock, purchase price $2.00 per share
Redeemable convertible preferred stock prior to IPO
Warrants to purchase shares												8,330
Purchase price \| $ / shares												$ 2.00
Series C Preferred Stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													9,247,089
Warrants to purchase shares					31,283									111,114			57,810	226,733
Warrants to purchase shares in cashless					22,809
Fair value of preferred warrants \| $					$ 0.1
Annual rate on cumulative dividends \| $ / shares													$ 0.2664
Cumulative accrued dividends \| $													$ 9.5
Liquidation preference per share \| $ / shares													$ 3.3299
Votes per share													1
Eligibility to elect number of directors													1
Number of annual instalments													3
Conversion shares of common stock	8,092,895
Series C Preferred Stock \| Stock Purchase Agreement \| bioMerieux
Redeemable convertible preferred stock prior to IPO
Purchase price \| $ / shares										$ 3.3299	$ 3.3299
Preferred stock, shares issued										600,618	1,501,546
Cash proceeds \| $										$ 2.0	$ 5.0
Series C Preferred Stock ,purchase price $3.3299 per share
Redeemable convertible preferred stock prior to IPO
Warrants to purchase shares					8,474
Purchase price \| $ / shares					$ 3.3299
Series C-1 Preferred Stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													544,332
Annual rate on cumulative dividends \| $ / shares													$ 0.2664
Cumulative accrued dividends \| $													$ 0.7
Liquidation preference per share \| $ / shares													$ 3.3299
Votes per share													0
Number of annual instalments													3
Conversion shares of common stock	544,332
Series D Preferred Stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													12,459,090
Warrants to purchase shares															38,828
Purchase price \| $ / shares								$ 3.67
Preferred stock, shares issued								12,420,262
Cash proceeds \| $								$ 45.4
Annual rate on non-cumulative dividends \| $ / shares													$ 0.2936
Liquidation preference per share \| $ / shares													$ 3.67
Votes per share													1
Number of annual instalments													3
Conversion shares of common stock	12,420,262
Series D-1 Preferred Stock
Redeemable convertible preferred stock prior to IPO
Preferred stock, authorized shares													2,113,902
Purchase price \| $ / shares						$ 4.021
Preferred stock, shares issued						2,113,902
Cash proceeds \| $						$ 8.4
Annual rate on non-cumulative dividends \| $ / shares													$ 0.3217
Liquidation preference per share \| $ / shares													$ 4.021
Votes per share													1
Number of annual instalments													3
Conversion shares of common stock	2,113,902

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units - Common stock reserved (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Shares reserved for future awards under compensation plan	2,433,999	3,500,620
Common stock reserved	5,348,442	6,013,745
Outstanding warrants
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Common stock reserved	76,041	86,090
Common stock options and unvested restricted common stock
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Common stock reserved	2,838,402	2,427,035

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units - Warrants (Details) - Outstanding warrants	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Number outstanding
Outstanding at the beginning of the period (in shares)	86,090
Issued (in shares)	10,000
Exercised (in shares)	(16,718)
Cancelled (in shares)	(3,331)
Outstanding at the end of the period (in shares)	76,041
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) \| $ / shares	$ 9.14
Issued (in dollars per share) \| $ / shares	4.83
Exercised (in dollars per share) \| $ / shares	11.73
Cancelled (in dollars per share) \| $ / shares	11.73
Outstanding at the end of the period (in dollars per share) \| $ / shares	$ 10.10
Obligation to issue warrants, in shares	93,341

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units - Share-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Share-based compensation expense	$ 4,884	$ 2,168	$ 928
Cost of product revenue
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Share-based compensation expense	55	24	6
Cost of service and other revenue
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Share-based compensation expense	173	52	12
Research and development
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Share-based compensation expense	513	180	59
General and administrative
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Share-based compensation expense	$ 4,143	$ 1,912	$ 851

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units - Stock-based award plans (Details) - shares		3 Months Ended
	Jan. 01, 2019	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Common stock available for future awards (in shares)				5,348,442	6,013,745
2007 Plan
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Shares authorized under the plan (in shares)		4,350,035			1,042,314	3,852,213	3,229,935
Additional shares authorized		497,822	622,227
Shares available for grant under the plan (in shares)				4,393	1,042,314
Annual increase in the shares available for grant under the plan (as a percent of shares of common stock outstanding)				4.00%
2017 Plan
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Additional shares authorized	895,169
2017 ESPP
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Shares authorized under the plan (in shares)					208,463
Shares available for grant under the plan (in shares)				425,533
Annual increase in the shares available for grant under the plan (as a percent of shares of common stock outstanding)					1.00%
Outstanding stock options
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Options outstanding (in shares)				2,476,911	2,249,843		1,119,671
Outstanding stock options \| 2007 Plan
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Options outstanding (in shares)					2,249,843
Common stock issued and outstanding pursuant to the exercise of options (in shares)					571,838
Common stock available for future awards (in shares)					399,379
Shares authorized under the plan (in shares)					2,490,290
Restricted and unrestricted stock awards \| 2007 Plan
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Common stock issued and outstanding pursuant to restricted or unrestricted stock awards (in shares)					1,128,975

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units - Stock options (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Aggregate intrinsic value
Weighted-average fair value of options granted		$ 7.19	$ 4.52	$ 2.41
Share-based compensation expense		$ 4,884	$ 2,168	$ 928
Outstanding stock options
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Options expiration period (in years)		10 years
Number outstanding
Outstanding at the beginning of the period (in shares)		2,249,843	1,119,671
Granted (in shares)		729,224	1,281,135
Exercised (in shares)		(407,901)	(90,265)
Cancelled or forfeited (in shares)		(94,255)	(60,698)
Outstanding at the end of the period (in shares)	2,476,911	2,476,911	2,249,843	1,119,671
Vested and expected to vest at the end of the period (in shares)	2,476,911	2,476,911
Exercisable at the end of the period (in shares)	1,143,480	1,143,480
Weighted-average exercise price
Outstanding at the beginning of the period (in dollars per share)		$ 6.05	$ 2.99
Granted (in dollars per share)		18.36	8.46
Exercised (in dollars per share)		4.57	2.25
Cancelled or forfeited (in dollars per share)		13.16	6.16
Outstanding at the end of the period (in dollars per share)	$ 9.65	9.65	$ 6.05	$ 2.99
Vested and expected to vest at the end of the period (in dollars per share)	9.65	9.65
Exercisable at the end of the period (in dollars per share)	$ 5.68	$ 5.68
Remaining contractual life
Outstanding (in years)		7 years 8 months 24 days	7 years 9 months 18 days	6 years 9 months 18 days
Vested and expected to vest at the end of the period (in years)		7 years 8 months 24 days
Exercisable at the end of the period (in years)	6 years 6 months 5 days
Aggregate intrinsic value
Outstanding	$ 22,108	$ 22,108	$ 34,695	$ 5,796
Vested and expected to vest at the end of the period	22,108	22,108
Exercisable at the end of the period	14,440	$ 14,440
Weighted-average fair value of options granted		$ 7.19	$ 4.52
Share-based compensation expense		$ 2,700	$ 1,500	200
Intrinsic value of stock options exercised		5,300	$ 1,100	$ 400
Total unrecognized compensation cost related to unvested stock options	$ 6,800	$ 6,800
Period of recognition of unrecognized compensation cost		2 years 2 months 23 days
Outstanding stock options \| Subject to a four year vesting schedule with 25% vesting on the first anniversary and the remaining vesting ratably on a monthly basis over the remaining three years
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Vesting period (in years)		4 years
Vesting percentage 1 (as a percent)		25.00%
Outstanding stock options \| Subject to vesting with 50% vesting on December 31, 2018 and December 31, 2019
Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Vesting period (in years)		3 years
Vesting percentage 1 (as a percent)		75.00%

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units - Restricted stock (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2015	Dec. 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted-average grant date fair value per share
Share-based compensation expense			$ 4,884	$ 2,168	$ 928
Restricted stock
Number of restricted stock
Unvested restricted common stock at the beginning of the period (in shares)			177,192	376,248	623,869
Granted (in shares)			0	0
Vested (in shares)			(137,386)	(199,056)	(247,621)
Unvested restricted common stock at the end of the period (in shares)			39,806	177,192	376,248
Weighted-average grant date fair value per share
Unvested restricted common stock at the beginning of the period (in dollars per share)			$ 3.11	$ 3.12	$ 3.12
Vested (in dollars per share)			3.11	3.12	3.09
Unvested restricted common stock at the end of the period (in dollars per share)			$ 3.12	$ 3.11	$ 3.12
Share-based compensation expense			$ 400	$ 600	$ 700
Total unrecognized compensation cost related to unvested stock awards			$ 0
Period of recognition of unrecognized compensation cost			0 years
Aggregate fair value of restricted stock awards			$ 2,400	$ 1,900	$ 1,100
2007 Plan \| Restricted stock \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)		4 years
Number of restricted stock
Granted (in shares)		78,912
2007 Plan \| Restricted stock \| Executive
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			4 years
Number of restricted stock
Granted (in shares)	781,060
2007 Plan \| Restricted stock \| Executive \| Subject to a four year vesting schedule with 25% vesting on the first anniversary and the remaining vesting ratably on a monthly basis over the remaining three years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage 1 (as a percent)	25.00%
2007 Plan \| Restricted stock \| Executive \| Subject to vesting with 50% vesting on December 31, 2018 and December 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			3 years
Vesting percentage 1 (as a percent)	75.00%

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units - Restricted stock units (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted-average grant date fair value per share
Share-based compensation expense		$ 4,884	$ 2,168	$ 928
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock issued (in shares)		422,027
Number of restricted stock units
Granted (in shares)		422,027
Vested (in shares)		(99,990)
Cancelled or Forfeited (in shares)		(375)
Unvested restricted common stock at the end of the period (in shares)		321,662
Weighted-average grant date fair value per share
Granted (in dollars per share)		$ 15.65
Vested (in dollars per share)		15.02
Cancelled or Forfeited (in dollars per share)		18.40
Unvested restricted common stock at the end of the period (in dollars per share)		$ 15.84
Share-based compensation expense		$ 1,700
Total unrecognized compensation cost related to unvested stock awards		$ 4,900
Period of recognition of unrecognized compensation cost		7 months 6 days
2017 Plan \| Restricted stock units \| Subject to a four year vesting schedule with 25% vesting on the first anniversary and the remaining vesting ratably on a monthly basis over the remaining three years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock issued (in shares)		84,637
Vesting period 1		4 years
Vesting period 2		3 years
Vesting percentage 1 (as a percent)		25.00%
Vesting percentage 2 (as a percent)		75.00%
Number of restricted stock units
Granted (in shares)		84,637
2017 Plan \| Restricted stock units \| Subject to vesting with 50% vesting on December 31, 2018 and December 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock issued (in shares)		18,200
Vesting percentage 1 (as a percent)		50.00%
Vesting percentage 2 (as a percent)		50.00%
Number of restricted stock units
Granted (in shares)		18,200
2017 Plan \| Restricted stock units \| Subject to a four year vesting schedule with 25% vesting on each anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock issued (in shares)		3,300
Vesting period 1		4 years
Vesting percentage 1 (as a percent)		25.00%
Number of restricted stock units
Granted (in shares)		3,300
2017 Plan \| Restricted stock units \| Vesting on December 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock issued (in shares)		15,890
Number of restricted stock units
Granted (in shares)		15,890
2017 Plan \| Restricted stock units \| Vested on August 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock issued (in shares)		50,000
Number of restricted stock units
Granted (in shares)		50,000
2017 Plan \| Restricted stock units \| Vests evenly over 40 months on the last day of each month starting September 30,2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock issued (in shares)	250,000	250,000
Vesting period 3		40 months
Number of restricted stock units
Granted (in shares)	250,000	250,000

Commitments and contingencies - License agreements and Lease commitments (Details)		12 Months Ended
	Oct. 02, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
License agreements
Drawing capacity	$ 1,000,000
Letter of credit will be reduced at 41 months after the commencement date	750,000	$ 750,000
Letter of credit will be reduced at 65 months after the commencement date	$ 250,000	250,000
Minimum future rent payments under the lease agreement
2019		1,172,000
2020		2,013,000
2021		3,290,000
2022		3,372,000
2023 and Forward		29,207,000
Total		39,054,000
Rent expense		1,600,000	$ 1,100,000	$ 1,100,000
Other non-current liabilities
License agreements
Deferred rent expense		300,000
Other accrued expenses \| Maximum
License agreements
Deferred rent expense		100,000
Company headquarters
License agreements
Term of operating lease	137 months
Square footage of office and laboratory space	92,000
License agreements \| Tufts
License agreements
Royalty expense		700,000	500,000	300,000
Other licenses
License agreements
Royalty expense		400,000	$ 200,000	$ 200,000
Annual minimum royalty to be paid under the license agreement		$ 50,000

Commitments and contingencies - Development and supply agreement and Legal contingencies (Details) - STRATEC Biomedical - Development and supply agreement $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Commitments and contingencies
Amount payable to counterparty	$ 1.5
Period to purchase minimum number of commercial units	7 years
Fee payable on shortfall of commercial units purchase	$ 11.1
Issuance of supply warrants on termination of agreement, number (in shares) \| shares	93,341
Issuance of supply warrants on termination of agreement, value per share (in dollars per share) \| $ / shares	$ 0.003214

Long Term Debt (Details) - USD ($)					1 Months Ended				12 Months Ended
Long Term Debt (Details) - USD ($)	Feb. 01, 2018	Dec. 01, 2015	Mar. 04, 2015	Apr. 14, 2014	Aug. 31, 2018	Jul. 31, 2018	Jun. 30, 2018	Jan. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2018	Oct. 02, 2018	Sep. 03, 2018	Apr. 01, 2018	Jul. 31, 2017	Mar. 31, 2017	Jul. 31, 2016	Apr. 30, 2016
Long Term Debt
Amount borrowed under the loan facility									$ 7,763,000
Principal payment on loan					$ 0	$ 0	$ 0
Total facility available													$ 1,000,000
Non-cash interest expense									200,000	$ 200,000	$ 400,000
Unamortized debt issuance costs									100,000
Long Term Debt									7,623,000	$ 4,346,000
Loan agreement
Long Term Debt
Fair value of warrants issued				$ 100,000
Debt issuance costs				100,000
Amount of investment by lender				$ 1,000,000
Additional amounts available to borrow									0
Loan agreement \| Minimum
Long Term Debt
Interest rate (as a percent)				8.00%
Loan agreement \| Maximum
Long Term Debt
Maximum amount to invest				$ 1,000,000
Conversion amount				$ 1,000,000
Amendment 1 to loan agreement
Long Term Debt
Fair value of warrants issued			$ 100,000
Amount borrowed under the loan facility			5,000,000
Principal payment on loan		$ 300,000
Term charge			200,000
Amendment 1 to loan agreement \| Minimum
Long Term Debt
Amount to be received under equity financing			$ 10,000,000
Amendment 2 to loan agreement
Long Term Debt
Fair value of warrants issued								$ 100,000
Amount borrowed under the loan facility								5,000,000										$ 3,000,000
Term charge								100,000
Total facility available								$ 15,000,000											$ 13,000,000
Remaining facility expired unexercised																			$ 2,000,000
Amendment 3 to loan agreement
Long Term Debt
Amount borrowed under the loan facility														$ 0			$ 5,000,000
Term charge	$ 50,000
Total facility available															$ 23,000,000		18,000,000
Amendment 4 to loan agreement \| Maximum
Long Term Debt
Interest cap																10.00%
Amendment 5 to loan agreement
Long Term Debt
Principal payment on loan									1,400,000
Term charge					80,000				$ 500,000
Cost incurred upon execution					$ 50,000
Amendment 6 to loan agreement
Long Term Debt
Certificate of deposit associated with the lease												$ 1,000,000
Term loan
Long Term Debt
Amount borrowed under the loan facility																	$ 5,000,000
Prime rate \| Loan agreement
Long Term Debt
Margin on variable interest rate (as a percent)				5.25%

Long Term Debt - Debt payment obligations (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Debt payment obligations due based on principal payments
2019	$ 0
2020	7,763
Debt payment obligations	$ 7,763

Collaboration and license arrangements (Details) $ in Thousands		1 Months Ended				3 Months Ended								12 Months Ended
	Dec. 22, 2016 USD ($)	Dec. 31, 2018 USD ($)	Jan. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Nov. 30, 2012 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2013 USD ($)
Collaboration and license arrangements
Revenue related to the License and prototype unit																		$ 8,300
Revenues recognized						$ 10,877	$ 10,591	$ 8,643	$ 7,521	$ 6,589	$ 5,734	$ 5,213	$ 5,338	$ 37,632	$ 22,874	$ 17,585
Increase to deferred revenue														(1,849)	2,895	919
Joint development and license agreement
Collaboration and license arrangements
Consideration on collaboration activities					$ 10,000
Number of additional payments					2
Amount of additional payment					$ 5,000
Revenues recognized														2,100	1,100	200	$ 200
Deferred revenue	$ 1,200
2016 Amendment
Collaboration and license arrangements
Total allocable consideration	$ 3,200
Increase to deferred revenue													$ 2,000
Royalties		$ 0				$ 0								$ 0
2016 Amendment \| Maximum
Collaboration and license arrangements
Feasibility Period	3 years
2016 Amendment \| bioMerieux
Collaboration and license arrangements
Cash received			$ 2,000
Evaluation and option agreements and license agreement
Collaboration and license arrangements
Revenues recognized				$ 1,800
Deferred revenue										$ 1,200					$ 1,200
Number of agreements																	3
Number of fields for which the agreements were entered																	3
Non-refundable license fee				1,000												$ 1,000	$ 2,000
Amount allocated to the option of the related field				$ 800
Exclusive agreement
Collaboration and license arrangements
Consideration on collaboration activities		$ 500

Employee benefit-plans (Details) $ in Millions	12 Months Ended
Employee benefit-plans (Details) $ in Millions	Dec. 31, 2018 USD ($)
Employee benefit-plans
Contribution made to the 401 (k) Plan	$ 0.1

Business combinations (Details) - USD ($) $ in Thousands		12 Months Ended
Business combinations (Details) - USD ($) $ in Thousands	Jan. 30, 2018	Dec. 31, 2018
Fair value of assets acquired and liabilities assumed:
Goodwill		$ 1,308
Aushon acquisition
Fair value of consideration transferred:
Cash	$ 3,200
Obligation to issue cash	800
Total acquisition consideration	4,000
Fair value of assets acquired and liabilities assumed:
Cash and cash equivalents	199
Accounts receivable	210
Inventory	828
Prepaid expenses	71
Property and equipment and other non-current assets	180
Intangible Assets	2,950
Goodwill	1,308
Total assets acquired	5,746
Contractual obligations	(1,155)
Accounts payable and accrued liabilities	(591)
Net assets acquired	$ 4,000
Risk-adjusted discount rate used to determine fair value of intangible assets	14.40%
Transaction costs		$ 100

Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Rollforward of goodwill balance
Goodwill acquired	$ 1,308
Balance as of end of period	1,308
Purchased intangible assets
Gross Carrying Value	2,950
Accumulated Amortization	(601)
Net Carrying Value	2,348
Amortization expense	600	$ 0	$ 0
Estimated amortization expense
2019	582
2020	500
2021	403
2022	320
2023	238
2024 and thereafter	$ 305
Developed technology
Purchased intangible assets
Estimated Useful Life	7 years
Gross Carrying Value	$ 1,650
Accumulated Amortization	(378)
Net Carrying Value	$ 1,272
Weighted average life remaining	6 years 29 days
Customer relationships
Purchased intangible assets
Estimated Useful Life	10 years
Gross Carrying Value	$ 1,250
Accumulated Amortization	(208)
Net Carrying Value	$ 1,042
Weighted average life remaining	9 years 29 days
Tradenames
Purchased intangible assets
Estimated Useful Life	3 years
Gross Carrying Value	$ 50
Accumulated Amortization	(15)
Net Carrying Value	$ 35
Weighted average life remaining	2 years 29 days

Related party transactions (Details) - USD ($)	1 Months Ended		12 Months Ended
Related party transactions (Details) - USD ($)	Jun. 30, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 28, 2018
Related party transactions
Sale of preferred stock				$ 65,575,000
Commitment to sponsor agreement
Series D Preferred stock
Related party transactions
Sale of preferred stock		$ 45,600,000
Issuance of common stock in initial public offering, net of offering costs (in shares)		12,420,262
Series D-1 Preferred stock
Related party transactions
Sale of preferred stock	$ 8,500,000
Issuance of common stock in initial public offering, net of offering costs (in shares)	2,113,902
bioMerieux \| Joint development and license agreement
Related party transactions
Related party revenue			2,100,000	1,100,000	$ 200,000
Deferred revenue			0	2,100,000
bioMerieux \| Series C Preferred stock
Related party transactions
Sale of preferred stock						$ 7,000,000
Principal stockholders, officers and directors \| Series D Preferred stock
Related party transactions
Sale of preferred stock		$ 22,900,000
Director \| Series D-1 Preferred stock
Related party transactions
Sale of preferred stock	$ 1,000,000
Tufts \| License Agreement
Related party transactions
Royalty Expense			700,000	500,000	300,000
License Costs					$ 400,000
Harvard University \| Maximum
Related party transactions
Related party revenue			100,000	$ 100,000
PPH \| Maximum
Related party transactions
Commitment to sponsor agreement							$ 120,000
Total contributions to sponsor agreement			$ 100,000

Restricted Cash (Details) - USD ($)	Dec. 31, 2018	Oct. 02, 2018
Restricted Cash
Letter of Credit drawable by the lessor	$ 1,000,000
Letter of credit will be reduced at 41 months after the commencement date	750,000	$ 750,000
Letter of credit will be reduced at 65 months after the commencement date	$ 250,000	$ 250,000

Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenue	$ 10,877	$ 10,591	$ 8,643	$ 7,521	$ 6,589	$ 5,734	$ 5,213	$ 5,338	$ 37,632	$ 22,874	$ 17,585
Operating Expense:
Total costs of goods sold and services									19,684	12,887	9,837
Research and development (including stock compensation of $513, $180, and $59 for the years ended December 31, 2018, and 2017, and 2016, respectively)	4,045	4,411	3,705	3,644	3,927	4,224	3,903	4,250	15,805	16,304	16,993
Selling, general and administrative (including stock compensation of $4,143, $1,912, and $851 for the years ended December 31, 2018, 2017, and 2016, respectively)	10,577	8,846	7,579	6,691	6,047	4,728	4,747	4,166	33,693	19,688	12,466
Total operating expenses	20,291	18,253	15,954	14,684	13,682	12,121	11,682	11,394	69,182	48,879
Loss from operations	(9,414)	(7,662)	(7,311)	(7,163)	(7,093)	(6,387)	(6,469)	(6,056)	(31,550)	(26,005)	(21,711)
Interest income (expense), net	24	30	16	(24)	(216)	(240)	(240)	(255)	46	(951)	(1,298)
Other (expense) income, net	81	(25)	(48)	(15)	(73)	13	77	(80)	(7)	(63)	(164)
Tax expense	(25)								(25)
Net loss	(9,334)	(7,657)	(7,343)	(7,202)	(7,382)	(6,614)	(6,632)	(6,391)	(31,536)	(27,019)	(23,173)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss	(9,334)	(7,657)	(7,343)	(7,202)	(7,382)	(6,614)	(6,632)	(6,391)	(31,536)	(27,019)	(23,173)
Accretion of preferred stock to redemption value					(809)	(1,112)	(1,099)	(1,090)		(4,110)	(4,437)
Accrued dividends on preferred stock					(11)	(16)	(16)	(16)		(59)	(8)
Net loss attributable to common stockholders	$ (9,334)	$ (7,657)	$ (7,343)	$ (7,202)	$ (8,202)	$ (7,742)	$ (7,747)	$ (7,497)	$ (31,536)	$ (31,188)	$ (27,618)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.42)	$ (0.35)	$ (0.34)	$ (0.33)	$ (1.06)	$ (3.13)	$ (3.21)	$ (3.18)	$ (1.43)	$ (8.30)	$ (12.89)
Weighted-average common shares outstanding, basic and diluted	22,221,305	22,670,786	21,890,978	21,788,605	7,731,514	2,475,166	2,416,984	2,357,503	21,994,317	3,756,954	2,142,840
Product revenue
Total revenue	$ 7,458	$ 5,962	$ 5,200	$ 4,745	$ 4,069	$ 3,293	$ 3,337	$ 3,425	$ 23,365	$ 14,124	$ 10,601
Operating Expense:
Total costs of goods sold and services	3,734	3,277	2,945	2,773	2,169	1,905	1,834	1,834	12,729	7,742	6,299
Service and other revenue
Total revenue	3,419	3,017	3,174	2,507	2,252	2,172	1,608	1,644	12,117	7,676	5,012
Operating Expense:
Total costs of goods sold and services	$ 1,935	1,719	1,725	1,576	1,539	1,264	1,198	1,144	6,955	5,145	3,163
Collaboration and license revenue
Total revenue		$ 1,612	$ 269	$ 269	$ 268	$ 269	$ 268	$ 269	$ 2,150	$ 1,074	1,972
Operating Expense:
Total costs of goods sold and services											$ 375