Summary of significant accounting policies | Summary of significant accounting policies Use of estimates The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, calculating the standalone selling price of products and services for revenue recognition, the valuation of inventory, and the valuation of stock-based awards. The Company bases its estimates on historical experience, known trends and other market-specific and relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates. Risk of concentrations of credit, significant customers and significant suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents, short-term and long-term investments and accounts receivable. Periodically, the Company maintains deposits in accredited financial institutions in excess of federally insured limits. The Company maintains its cash and cash equivalents with financial institutions that management believes to be of high credit quality. The Company has not experienced any losses on such accounts or any other-than-temporary losses with respect to its cash equivalents and investments and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Significant customers are those which represent more than 10% of the Company’s total revenue or accounts receivable balance at each respective balance sheet date. The following table presents customers that represent 10% or more of the Company’s total revenue: Year Ended December 31, 2022 2021 Customer A 22.8 % 16.7 % 22.8 % 16.7 % The following table presents customers that represent 10% or more of the Company’s accounts receivable: Year Ended December 31, 2022 2021 Customer A 21.4 % 19.5 % Customer B 16.7 % * Customer C 11.8 % * Customer D * 12.6 % Customer E * 10.6 % Customer F * 10.0 % 49.9 % 52.7 % ______________________________ * – less than 10% The Company relies on third parties for the supply and manufacture of certain of its products as well as logistics. In instances where these parties fail to perform their obligations, the Company may be unable to find alternative suppliers to satisfactorily deliver its products to its customers on time, if at all, which could have a material adverse effect on the Company’s operating results, financial condition and cash flows and damage its customer relationships. There are no significant concentrations around a single third-party supplier or manufacturer for the year ended December 31, 2022 or 2021. Debt issuance costs The Company capitalizes certain legal and other third-party fees that are directly associated with the issuance of debt as debt issuance costs. Debt issuance costs are recorded as a direct reduction of the carrying amount of the associated debt on the consolidated balance sheets and amortized as interest expense on the consolidated statement of operations using the effective interest method, which approximates the straight-line method. As of December 31, 2022 and 2021, the Company had no debt issuance costs on its consolidated balance sheets. During the year ended December 31, 2022 and 2021, the Company recorded zero and $0.4 million, respectively, in amortization of debt issuance costs within interest income (expense) in the consolidated statement of operations. Cash equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash equivalents that are readily convertible to cash are stated at cost, which approximates fair value. At December 31, 2022 and 2021, the Company held cash of $0.2 million and $0.3 million in banks located outside of the U.S., respectively. Restricted cash As of December 31, 2022 and 2021, the Company was required to maintain guaranteed investment certificates of $0.3 million, with maturities of three months to one year that are subject to an insignificant risk of changes in value. The guaranteed investment certificates are held for the benefit of landlords in connection with operating leases which have remaining terms of greater than one year and are classified as restricted cash (non-current) on the Company’s consolidated balance sheet. Investments The Company’s short-term and long-term investments are classified as available-for-sale and recorded at fair value based upon market prices at period end. Unrealized gains and losses are recorded in accumulated other comprehensive income as a separate component of stockholders’ equity. Realized gains and losses and declines in value of investments determined to be other than temporary are included as a component of interest income (expense), net in the consolidated statement of operations. The costs of investments for purposes of computing realized and unrealized gains and losses is based on the specific identification method. The Company evaluates its short-term and long-term investments with unrealized losses for other-than-temporary impairment. When assessing investments for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be other-than-temporary, the Company reduces the investment to fair value through a charge to the consolidated statement of operations. No such adjustments were necessary during the periods presented. The Company’s short-term investments as of December 31, 2022 and 2021 had maturities of less than one year, and long-term investments as of December 31, 2022 and 2021 had maturities greater than one year. Accounts receivable Accounts receivable are customer obligations that are unconditional. Accounts receivable are presented net of an allowance for doubtful accounts, which represents an estimate of amounts that may not be collectible. The Company performs ongoing credit evaluations of its customers and, if necessary, provides an allowance for doubtful accounts and expected losses. The Company writes off accounts receivable against the allowance when it determines a balance is uncollectible and no longer actively pursues collection of the receivable. The Company does not have any off-balance-sheet credit exposure related to customers. As of December 31, 2022 and 2021, the Company recorded zero allowance for doubtful accounts. Additionally, for the years ended December 31, 2022 and 2021, the Company recorded zero provision for bad debts or recoveries. Inventory Inventory is valued at the lower of cost or net realizable value. Cost is computed using the first-in, first-out method. The Company regularly reviews inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, records charges to write down inventories to their estimated net realizable value, after evaluating historical sales, future demand, market conditions and expected product life cycles. Such charges are classified as cost of product revenue in the consolidated statements of operations. Any write-down of inventory to net realizable value creates a new cost basis. Property and equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset, as follows: Estimated Useful Life Manufacturing and laboratory equipment 5-10 years Computer hardware and software 3 years Office furniture and fixtures 5-7 years Leasehold improvements Shorter of remaining life of lease or useful life Estimated useful lives are periodically assessed to determine if changes are appropriate. Maintenance and repairs are charged to expense as incurred. When assets are retired or otherwise disposed of, the cost of these assets and related accumulated depreciation or amortization are eliminated from the consolidated balance sheet and any resulting gains or losses are included in the consolidated statement of operations in the period of disposal. Costs for capital assets not yet placed into service are capitalized as construction-in-progress and depreciated once placed into service. Software development costs The Company accounts for software development costs for internal-use software under the provisions of ASC 350-40, “Internal-Use Software” (“ASC 350”). Accordingly, certain costs to develop internal-use computer software are capitalized, provided these costs are expected to be recoverable. There was $1.4 million and $1.3 million of software development costs capitalized in other long-term assets at December 31, 2022 and 2021, respectively, net of accumulated amortization of $0.4 million and $0.1 million, respectively. The capitalized costs are being amortized on a straight-line basis over the initial subscription term of five years. There was $0.3 million and $0.1 million of amortization expense recorded in the consolidated statement of operations for the years ended December 31, 2022 and 2021. Impairment of long-lived assets Long-lived assets consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized in loss from operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss is based on the excess of the carrying value of the impaired asset group over its fair value, determined based on discounted cash flows. The Company did not record any impairment losses on long-lived assets during the years ended December 31, 2022 or 2021. Fair value measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents, investments, and its redeemable convertible preferred stock warrant liability are carried at fair value, determined according to the fair value hierarchy described above (see Note 3). The carrying values of the Company’s accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate their fair values due to the short-term nature of these assets and liabilities. Product warranties The Company offers a one-year limited assurance warranty on system sales, which is included in the selling price. Product warranties provide assurance that the Company’s product functions in accordance with standard specifications. Warranties cover for repairs and replacements when the product does not function in accordance with agreed specifications. The standard assurance warranty does not cover, and no warranty is provided for, parts which by their nature are normally required to be replaced periodically. The accrued warranty cost is based on estimated material, labor and other costs that the Company expects to incur to fulfill the warranty obligation. Estimates are primarily based on historical information, current cost data and future forecasts. The Company periodically assesses the adequacy of the warranty accrual and adjusts the amount as necessary. If the historical data used to calculate the adequacy of the warranty accrual are not indicative of future requirements, additional or reduced warranty accrual may be required. The warranty accrual is included in accrued expenses and other current liabilities in the consolidated balance sheets. The following table presents a summary of changes in the amount reserved for warranty cost (in thousands): Year Ended December 31, 2022 2021 Balance, beginning of the period $ 598 $ 637 Warranty provisions 646 — Warranty repairs (372) (39) Balance, end of the year $ 872 $ 598 Classification and accretion of redeemable convertible preferred stock Prior to the IPO and the conversion of redeemable convertible preferred stock to Class A and Class B common stock, the Company had classified redeemable convertible preferred stock outside of stockholders’ equity because the shares contained certain redemption features that were not solely within the control of the Company. Costs incurred in connection with the issuance of each series of redeemable convertible preferred stock was recorded as a reduction of gross proceeds from issuance. The Company recorded periodic accretion to the carrying values of its outstanding redeemable convertible preferred stock such that the carrying value of the redeemable convertible preferred stock would have been equal to the redemption value at the earliest date of redemption. Adjustments to the carrying values of the redeemable convertible preferred stock to record this accretion at each reporting date were considered deemed dividends, which adjusted retained earnings (or in the absence of retained earnings, additional paid-in capital) and increased or decreased net loss attributable to common stockholders in computing basic and diluted earnings per share. Preferred stock warrant liability Prior to the IPO and the conversion of redeemable convertible preferred stock warrant liabilities to Class A common stock warrants, the Company classified warrants for the purchase of shares of its redeemable convertible preferred stock (see Notes 3 and 10) as a liability on its consolidated balance sheets as these warrants were freestanding financial instruments that may have required the Company to transfer assets upon exercise. The warrant liability was initially recorded at fair value on the issuance date of each warrant and was subsequently remeasured to fair value at each reporting date using the Black-Scholes pricing model. Changes in the fair value of the warrant liability were recognized as a component of other income (expense) in the consolidated statements of operations. Changes in the fair value of the preferred stock warrant liability were recognized up until the warrants qualified for equity classification upon IPO. Segment information The Company determined its operating segment after considering the Company’s organizational structure and the information regularly reviewed and evaluated by the Company’s chief operating decision maker (“CODM”) in deciding how to allocate resources and assess performance. The Company has determined that its CODM is its Chief Executive Officer. The CODM reviews the financial information on a consolidated basis for purposes of evaluating financial performance and allocating resources. On the basis of these factors, the Company determined that it operates and manages its business as one operating segment, that develops, manufactures, markets and sells systems and related LIMS connection software, consumables and services; and, accordingly, has one reportable segment for financial reporting purposes. Substantially all of the Company’s long-lived assets are held in the United States. Revenue recognition Under ASC 606, revenue is recognized when a 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 order to achieve this core principle, the Company applies the following five steps when recording revenue: (1) identify the contract, or contracts, with the customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract and (5) recognize revenue when, or as, performance obligations are satisfied. The Company derives revenue from the sale of its products and services through direct sales representatives and distributors. The Company’s arrangements are generally noncancelable and nonrefundable after ownership passes to the customer or distributor. Product revenue The Company derives product revenue primarily from the sale of its systems, optional LIMS connection software, which facilitates the transfer of data captured by the system to the customer’s existing LIMS software, and proprietary consumables. Revenue is recognized when control of the products is transferred to the customer. Transfer of control is generally at shipment or delivery, depending on contractual terms, and occurs when title and risk of loss transfers to the customer, which represents the point in time when the customer obtains the use of and substantially all of the benefits of the product. Upon delivery, the System is fully functional for use by the customer. As such, the Company’s performance obligation related to product sales is satisfied at a point in time. The Company’s principal terms of sale are free carrier shipping point. Service revenue The Company derives service revenue primarily from validation services, service contracts and field service (including installation). The Company’s validation services include validation and documentation services performed utilizing systems purchased by the customer. Service contracts are around-the-clock maintenance support which can be purchased by the customer after the expiration of the one-year assurance warranty included with each system purchase. Field service revenue primarily consists of services provided by field service engineers to install the system at the customer site and perform two preventative maintenance services during the warranty period. Service revenue is recognized over time using an input method based on time lapsed for service contracts and output method based on milestone achieved for validation services and field service. Performance obligations A performance obligation is a promise in a contract to transfer a distinct product or service to a customer that are both capable of being distinct, whereby the customer can benefit from the product or service either on its own or together with other resources that are readily available, and are distinct in the context of the contract, whereby the transfer of the product or service is separately identifiable from other promises in the contract. The Company’s main performance obligations in customer arrangements are systems, LIMS connection software, consumables, validation services, service contracts, and field service. Payment terms Payment terms for customer orders are typically between 30 to 90 days after the shipment or delivery of the product. For certain products, services and customer types, the Company requires payment before the products or services are delivered to, or performed for, the customer. None of the Company’s contracts contain a significant financing component. Multiple performance obligations with an arrangement The Company’s contracts may include multiple performance obligations when customers purchase a combination of products and services such as system sold together with the LIMS connection software, consumables or services. For these arrangements, the Company allocates the contract’s transaction price to each performance obligation on a relative standalone selling price basis using the Company’s best estimate of the standalone selling price of each distinct product or service in the contract. The primary methods used to estimate standalone selling prices are based on the prices observed in standalone sales to customers or cost-plus margin depending on the nature of the obligation and available evidence of fair value. Allocation of the transaction price is determined at contract’s inception. Remaining performance obligations The Company does not disclose the value of remaining performance obligations for (i) contracts with an original contract term of one year or less, (ii) contracts for which the Company recognizes revenue at the amount to which it has the right to invoice when that amount corresponds directly with the value of services performed, and (iii) variable consideration allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied distinct service that forms part of a single performance obligation. The Company does not have material remaining performance obligations associated with contracts with terms greater than one year. Contract balances from contracts with customers Contract assets arise from unbilled amounts in customer arrangements when revenue recognized exceeds the amount billed to the customer and the Company’s right to payment is conditional and not only subject to the passage of time. The Company had $0.1 million and $0.3 million in contract assets as of December 31, 2022 and 2021, respectively, included in prepaid expenses and other current assets. These balances relate to unbilled amounts with commercial customers as well as an amount in the prior year related to the BARDA agreement. Contract liabilities represent the Company’s obligation to transfer goods or services to a customer for which it has received consideration (or the amount is due) from the customer. The Company has a contract liability related to service revenue, which consists of amounts that have been invoiced but that have not been recognized as revenue. Amounts expected to be recognized as revenue within 12 months of the balance sheet date are classified as current deferred revenue and amounts expected to be recognized as revenue beyond 12 months of the balance sheet date are classified as noncurrent deferred revenue. The Company did not record any non-current deferred revenue as of December 31, 2022 or 2021. Deferred revenue was $4.7 million and $3.3 million at December 31, 2022 and 2021, respectively. Revenue recognized during the year ended December 31, 2022 that was included in deferred revenue at the prior year-end was $2.7 million. Revenue recognized during the year ended December 31, 2021 that was included in deferred revenue at the prior year-end was $3.8 million. Non-commercial revenue The Company has historically generated revenue from a long-term contract with the U.S. Department of Health and Human Services Biomedical Advanced Research and Development Authority (“BARDA”) a part of the U.S. government. The Company’s contracts with the U.S. government are typically subject to the Federal Acquisition Regulation (“FAR”) and are priced based on estimated or actual costs of producing goods or providing services. The FAR provides guidance on the types of costs that are allowable in establishing prices for goods or services provided under U.S. government contracts. In September 2017, the Company signed a contract with BARDA, which was subsequently modified on multiple occasions to increase the contract value and adjust the cost share reimbursement rate. Modifications were accounted for in accordance with the contract modification framework. The contract is a cost-reimbursable, cost-sharing arrangement, whereby BARDA reimburses the Company for a percentage of the total costs that have been incurred including indirect allowable costs. All funding under this contract was fully earned by the fourth quarter of 2021. However, the Company is now in the process of closing out its BARDA contract, which includes a true-up of actual reimbursable costs to those previously billed at provisional rates for each year of performance. Any true-up will be recognized as non-commercial revenue once finalized. Disaggregated revenue The Company disaggregates revenue based on the recurring and non-recurring, and commercial and non-commercial, nature of the underlying sale. Recurring revenue includes sales of consumables and service contracts. Non-recurring revenue includes sales of systems, LIMS connection software, validation services, field service, and revenue under the Company’s contract with BARDA. The following table presents the Company’s revenue by the recurring or non-recurring and commercial or non-commercial nature of the revenue stream (in thousands): Year Ended December 31, 2022 2021 Product and service revenue — recurring $ 10,983 $ 7,819 Product and service revenue — non-recurring 6,150 13,818 Non-commercial revenue — non-recurring — 1,595 Total revenue $ 17,133 $ 23,232 The following table presents the Company’s revenue by customer geography (in thousands): Year Ended December 31, 2022 2021 United States $ 8,767 $ 12,892 Germany 2,649 1,695 Switzerland 2,756 4,314 All other countries 2,961 4,331 Total revenue $ 17,133 $ 23,232 Contract acquisition costs The Company incurs and pays commissions on systems, LIMS connection software, validation services, consumables, and service contracts. The period of the related revenue stream is typically less than one year in duration, and as such, the Company applies the practical expedient to expense the costs in the period in which they were incurred. The Company does not pay commissions on non-commercial revenue with BARDA. Cost of revenue Cost of product revenue primarily consists of costs for raw material parts and associated freight, shipping and handling costs, royalties, contract manufacturer costs, salaries and other personnel costs including stock-based compensation expense, depreciation and amortization expense, scrap, warranty cost, inventory reserves, allocated information technology and facility-related costs, overhead and other costs related to those sales recognized as product revenue in the period. Cost of service revenue primarily consists of salaries and other personnel costs including stock-based compensation expense, travel costs, materials consumed when performing installations, validations and other services, allocated information technology and facility-related costs, costs associated with training and other expenses related to service revenue recognized in the period. Cost of non-commercial revenue primarily consists of salaries and other personnel costs including stock-based compensation expense, consulting expense, materials, travel and other costs related to revenue recognized as non-commercial revenue during the period. Shipping and handling fees Shipping and handling fees billed to customers for product shipments are recorded in product revenue in the consolidated statements of operations. Shipping and handling costs incurred for inventory purchases and product shipments are recorded in cost of product revenue in the consolidated statements of operations. Research and development costs Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities including, employee-related expenses, such as salaries, bonuses and other personnel costs including stock-based compensation expense, the cost of developing maintaining and improving new and existing products designs, the cost of hardware and software engineering, the cost of research materials and supplies, external costs of outside consultants engaged to conduct research and development services associated with the Company’s technology and products, and information technology and facilities expenses, which include direct and allocated expenses for rent, maintenance of facilities and insurance, as well as related depreciation and amortization. The costs incurred for the development of system software that will be sold are capitalized when technological feasibility has been established. The Company has continued to develop the software associated with its platform and products, and the associated costs have been expensed as incurred, when the nature of improvements did not significantly improve the performance or functionality of the software. Advertising costs Advertising costs are expensed as incurred and are included in sales and marketing expenses in the consolidated statements of operations. Advertising costs were $0.1 million during both of the years ended December 31, 2022 and 2021. Patent costs All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditures. Amounts incurred are classified within general and administrative expense in the consolidated statement of operations. Stock-based compensation The Company measures all stock-based awards granted to employees, officers and directors based on their fair value on the date of the grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award. The Company issues stock-based awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. Forfeitures are accounted for as they occur. The Company has not issued any stock-based awards with performance-based vesting conditions. The Company measures all restricted common stock and restricted stock units granted to employees based on the common stock value on the date of grant. The purchase price of the restricted common stock is the common stock value on the date of grant. The Company classifies stock-based compensation expense in its consolidated statement of operations in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model, which uses the following inputs: (i) the fair value per share of the common stock issuable upon exercise of the option, (ii) the expected term of the option, (iii) expected volatility of the price of the common stock, (iv) the risk-free interest rate, and (v) the expected dividend yield. The exercise price of the option cannot be less than the fair market value of a share of common stock on the date of grant. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards t |