Summary of Significant Accounting Policies | 2. Summary of significant accounting policies Basis of presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and the rules and regulations of the Securities and Exchange Commission (SEC) for reporting. 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, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the Chief Executive Officer. The Company views its operations and manages its business in one operating segment. Use of estimates The preparation of financial statements in conformity with GAAP requires management to make judgments, estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions, including knowledge about current events and expectations about actions the Company may take in the future, that the Company believes are reasonable under the circumstances. Actual results could vary from the amounts derived from management’s estimates and assumptions. During the year ended December 31, 2022, the Company shortened the useful life of certain lab equipment as a result of manufacturing changes brought about by the decision to no longer pursue the commercialization of the stand-alone Talis One COVID-19 test in the United States. This change in estimate resulted in $ 6.6 million of accelerated depreciation expense during the twelve months ended December 31, 2022. Reclassifications The accompanying statement of cash flows for the twelve-month period ended December 31, 2021 and the accompanying balance sheet as of the year ended December 31, 2021 reflects the Company's reclassification of grants receivables and unbilled grants receivables to accounts receivable, to conform to the presentation of the current period. The statement of cash flows for the twelve-month period ended December 31, 2021 reflects the Company's reclassification of the change in lease assets and liabilities into other long-term assets and liabilities, to confirm to the presentation in the current period. Fair value measurements The Company's financial assets carried at fair value consist of cash equivalents held in money market accounts that are valued using quoted prices in active markets for identical instruments. Due to their short-term nature, the carrying values for cash, accounts receivable and accounts payable approximate fair value. 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 and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. 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. 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 of the instrument. For nonfinancial assets, measurement at fair value in periods subsequent to their initial recognition is applicable if they are determined to be impaired. These assets generally include property and equipment and operating lease right-of-use assets. If measured at fair value in the balance sheets, these would generally be classified within Level 3 of the fair value hierarchy. Cash and cash equivalents The Company considers cash equivalents to be highly liquid investments with an original maturity at purchase of three months or less. These cash equivalents include holdings in money market funds that are invested in United States (U.S) Treasury obligations which are stated at fair value. Restricted cash Restricted cash consists of cash that serves as collateral for the Company’s standby letters of credit (see Note 6). Any cash that is legally restricted from use is classified as restricted cash. If the purpose of restricted cash relates to acquiring a long-term asset, liquidating a long-term liability, or is otherwise unavailable for a period longer than one year from the balance sheet date, the restricted cash is classified as a long-term asset, otherwise, restricted cash is included in current assets in the balance sheet. Accounts receivable, net Accounts receivable include trade receivables, unbilled receivables and grant receivables. The allowance for doubtful accounts reflects the current estimate of credit losses expected to be incurred over the life of the accounts receivable. The Company considers various factors in establishing, monitoring, and adjusting its allowance for doubtful accounts, including the aging of the accounts and aging trends and specific exposures related to particular customers. Accounts receivable are charged off after all reasonable means to collect the full amount have been exhausted. The Company has an immaterial allowance for doubtful accounts as of December 31, 2022 and 2021. Concentration of credit risk and other risks and uncertainties Financial instruments which potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash, and accounts receivables. The Company’s cash is deposited in accounts at large financial institutions and its cash equivalents are primarily held in prime and U.S. government money market funds. The Company believes it is not exposed to significant credit risk due to the financial strength of the depository institutions in which the cash and cash equivalents are held. The Company is subject to risks common to companies in the diagnostics industry including, but not limited to, uncertainties related to commercialization of products, regulatory approvals, and protection of intellectual property rights. Global economic conditions remain volatile resulting from the continuing and evolving effects of the COVID-19 pandemic, inflationary pressures, rising interest rates, the ongoing military conflict between Russia and Ukraine and related sanctions imposed against Russia and otherwise. The Company continues to evaluate the potential impact of these global issues on our current and future business operations, including our expenses, clinical trials and addressable markets as well as on our industry and healthcare system. The Company is dependent on key suppliers for certain manufacturing and research and development activities. An interruption in the supply of these materials could temporarily impact the Company’s ability to commercialize, manufacture inventory and perform research and development, testing and clinical trials related to its products. The Company is also dependent on its manufacturing partners that are critical to its ability to supply product to its end customers. Inventory Inventory, which consists of finished goods, is valued at the lower of cost or net realizable value. The Company determines the cost of inventory using the first-in, first-out method. Lower of cost or net realizable value is evaluated by considering obsolescence, excessive levels of inventory, deterioration and other factors. In order to assess the ultimate realization of inventories, the Company is required to make judgments as to future demand requirements compared to current or committed inventory levels. The Company periodically reviews its inventories for shelf life, excess or obsolescence and writes-down obsolete or otherwise unmarketable inventory to its estimated net realizable value. If the actual net realizable value is less than the carrying value, or if it is determined that inventory utilization will further diminish based on estimates of demand, additional inventory write-downs may be required. Inventory write-downs are recorded in cost of product sold and a new lower-cost basis for the inventory is established. Excess and obsolete inventory is primarily based on estimated forecasted sales, usage levels, and expiration dates and is recorded within cost of product sold. During the year ended December 31, 2022, the Company established a reserve against $ 4.4 million of inventory in excess of forecasted demand. Property and equipment Property and equipment are recorded at cost less accumulated depreciation. Depreciation is recorded using the straight-line method based on the estimated useful lives of the depreciable property or, for leasehold improvements, the remaining term of the lease, whichever is shorter. The useful lives of the assets are as follows: Estimated Useful Lab equipment 5 years Furnitures and fixtures 5 years Office and computer equipment 3 years Leasehold improvements Shorter of life of Upon sale or retirement of assets, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss is recognized in the statement of operations and comprehensive loss. Expenditures for maintenance and repairs are expensed as incurred. Construction in progress relates to new equipment having alternative future use that is being used to expand our research and development capabilities. Construction in progress includes the cost of construction and other direct costs attributable to the construction. Impairment of long-lived assets A long-lived asset may be impaired when the undiscounted cash flows expected to be generated by the asset (or asset group) are less than the asset’s carrying amount. Any required impairment loss would be measured as the amount by which the asset or asset group's carrying value exceeds its fair value, and would be recorded as a reduction in the carrying value of the related asset to its fair value and a charge to operating expense. The Company reviews the carrying amount of its long-lived assets, including property and equipment, for impairment whenever events indicate that the carrying amount of the assets may not be fully recoverable. During the year ended December 31, 2022, management concluded that the Company's decrease in market capitalization was a triggering event for potential impairments of our assets. A $ 3.6 million impairment of long-lived assets charge was recorded within selling, general and administrative expenses on the statement of operations and comprehensive loss for the year ended December 31, 2022. The operating lease impairment charge reduces the carrying value of the associated right-of-use assets to the estimated fair values. The fair values are estimated using a discounted cash flows approach on forecasted future cash flows derived from current market data including discount rate, rent and rent escalation rates, downtime and abatement assumptions. The fair value of our right-of-use assets may change as a result of a change in any of these inputs. There was no impairment recorded for the year ended December 31, 2021 . Leases At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease. The Topic requires a lessee to determine if an arrangement is a lease or contains a lease at contract inception, to recognize right-of-use ("ROU") assets and lease liabilities arising from operating and financing leases with terms longer than 12 months on the balance sheets and to disclose key information about leasing arrangements. The Company's lease agreements may include variable lease payments which are not included in the initial measurement of the right-of-use asset or lease liability due to the uncertainty of the payment amount and is recorded as lease cost in the period incurred. Lease expense is recognized on a straight-line basis over the lease term. For the Company's operating leases, the Company accounts for the lease and non-lease components as a single lease component, the lease liability is initially measured at the present value of the unpaid lease payments at lease commencement date. As most of the leases do not provide an implicit rate, the Company generally uses its incremental borrowing rate as the discount rate for the lease. The Company's incremental borrowing rate is the rate of interest it would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The operating lease right-of-use asset includes any lease payments to be made and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that it will exercise that option. The Company enters into certain manufacturing and supply arrangements with third-party suppliers that may contain embedded leases for the manufacturing of Talis One cartridges and instruments, which require highly specialized production lines. If it is determined that the Company controls the underlying assets during construction, the Company may be deemed to be the “owner” for accounting purposes during the construction period and may be required to capitalize the project costs on its balance sheet. As the Company has funded all of the construction costs, the recognition of a financing liability for amounts funded by the third-party supplier is not necessary. Revenue Recognition Product revenue, net The Company currently only generates revenues from its sales of third-party Antigen Tests. The Company obtains control of the product and assumes inventory risk before it is transferred to the customer and therefore reports revenue on the gross amount billed to the customer. The Company has recognized sales from two primary customer types: (i) direct customers including hospitals, urgent care centers, physician, public health and retail clinics, and (ii) sub-distributors. The Company recognizes revenue under Accounting Standards Codification Topic 606 (ASC 606), Revenue from Contracts with Customers, when a customer obtains control of promised goods or services, with a transaction price that reflects the consideration which the entity expects to receive in exchange for those goods or services. Transaction price does not include amounts subject to uncertainties unless it is probable that there will be no significant reversal of revenue when the uncertainty is resolved. If necessary, revenue is recorded net of variable consideration based on the amounts the Company expects to be earned or to be claimed on the related sales. The Company estimates the amount of its product sales that may result in returns or in price adjustments and records this estimate as a reduction of revenue in the period the related product revenue is recognized. The returned assets cannot be re-sold and have no value to the Company. The Company identifies the contract with a customer and determines the performance obligations and the contract price. The contract price is allocated to the distinct performance obligations in the contract and revenue is recognized when the performance obligations have been satisfied. A performance obligation is considered to be satisfied once the control of a product is transferred to the customer or the service is provided to the customer, meaning the customer has the ability to use and obtain the benefit of the goods or service, generally at product shipment. The Company recognizes receivables in an amount expected to be collected in a transaction. The Company’s payment terms are generally net 30 days of billing. Contracts do not contain significant financing components based on the typical period of time between delivery of products and collection of contract consideration. Certain types of customers may pay in advance of product delivery. In those instances, payment and delivery typically occur in the same month. The Company invoices its customers upon shipment of product and records its sales upon shipment in accordance with its standard terms and conditions, unless underlying customer contracts specify otherwise. When necessary, the Company invoices and collects sales tax from its customers for sales of products. The Company has elected to exclude sales tax from the measurement of the transaction price. Contract balances A receivable is recognized in the period the Company delivers goods or provides services or when the Company’s right to consideration is unconditional. The Company usually does not record contract assets because the Company has an unconditional right to payment upon satisfaction of the performance obligation, and therefore, a receivable is more commonly recorded than a contract asset. Receivables from contracts with customers are included within accounts receivable, net on the balance sheets. Contract liabilities include payments received in advance of performance under a contract and are satisfied as the associated revenue is recognized. When performance obligations are not transferred to a customer at the end of a reporting period, cash received associated with the amount allocated to those performance obligations is reflected as contract liabilities on the balance sheets and is deferred until control of these performance obligations is transferred to the customer. There are no contract liabilities as of December 31, 2022. Contract costs Under ASC 606, the Company is required to capitalize incremental costs to obtain customer contracts if the costs relate directly to a contract that can be specifically identified and expect to be recovered. These costs are required to be amortized to expense consistent with the transfer of the goods or services to the customer to which the asset relates. As a practical expedient, the Company recognizes any incremental costs to obtain a contract as an expense when incurred if the amortization period of the asset is one year or less. The Company did not have any capitalized contract costs as of and for the twelve months ended December 31, 2022 . Grant revenue and receivables Grants awarded to the Company for research and development by government entities are outside the scope of ASC 606. This is because the granting entities are not considered to be customers and are not receiving reciprocal value for their grant support provided to the Company. These grants provide the Company with payments for certain types of expenditures in return for research and development activities or for meeting certain development milestones over a contractually defined period. For efforts performed under these grant agreements, the Company’s policy is to recognize revenue when it is reasonably assured that the grant funding will be received as evidenced through the existence of a grant arrangement, amounts eligible for reimbursement are determinable and have been incurred and paid, the applicable conditions under the grant arrangements have been met, and collectability of amounts due is reasonably assured. Costs of grant revenue are recorded as a component of research and development expenses in the Company’s statements of operations and comprehensive loss. Grant funds received from third parties are recorded as revenue if the Company is deemed to be the principal participant in the arrangement. If the Company is not the principal participant, the funds from grants are recorded as a reduction to research and development expense. Reimbursable costs paid prior to being billed are recorded as unbilled grant receivables. Funds received in advance are recorded as deferred grant revenue. Management has determined that the Company is the principal participant under the Company’s grant agreements, and accordingly, the Company records amounts earned under these arrangements as grant revenue. Costs of product sold Costs of product sold include material costs, direct labor, provisions for inventory write-downs and shipping and handling costs incurred. The Company reports product shipment costs within cost of products sold in the accompanying statements of operations. Research and development costs Research and development expenses include certain payroll and personnel expenses, laboratory supplies, consulting costs, external contract research and development expenses, allocated overhead and facility occupancy costs. Costs to develop the Company’s technologies, including software, are recorded as research and development expense except for costs that meet the criteria to be capitalized as internal-use software costs. The Company does not capitalize pre-launch inventory costs until future commercialization is considered probable and the future economic benefit is expected to be realized. Capitalizing pre-launch inventory costs will not occur prior to obtaining an EUA or other FDA marketing authorization, commercialization is considered probable and future economic benefit can be asserted. The Company records such costs as research and development expenses, or if used in marketing evaluations records such costs as selling, general and administrative expenses. All materials, equipment, and external consulting costs associated with developing aspects of the production line that do not have an alternative future use are expensed as research and development costs until regulatory approval or clearance is obtained and commercialization is probable. Materials, equipment, and external consulting costs associated with developing aspects of the production line that are deemed to have an alternative future use are capitalized as property and equipment, assessed for impairment and depreciated over their related useful lives. In 2021, the Company completed work on production lines to automate the production of its Talis One cartridges for the COVID-19 test. The Company incurred $ 69.6 million as part of the Company’s effort to scale-up its manufacturing capacity including costs incurred for high capacity production equipment in the twelve months ended December 31, 2021. During the year ended December 31, 2021 the Company charged $ 11.8 million of pre-launch inventory relating to cartridges and $ 21.7 million of pre-launch inventory relating to instrument components to research and development expense, respectively. The Company makes estimates of its accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances at that time through discussions internally and with service providers to confirm the accuracy of progress and stage of completion. The Company’s understanding of the status and timing of services performed relative to the actual status and timing of services performed requires judgment and actual results may vary. Preferred stock As part of the Company's IPO, certain shares of the Company's historical convertible preferred stock converted into shares of the Company's Series 1 convertible preferred stock. The Company records the Series 1 convertible preferred stock at par value on the date of conversion. The Company has classified its Series 1 convertible preferred stock as permanent equity within the accompanying balance sheet at December 31, 2022 and 2021 due to the immaterial liquidation value of the shares. The Company also evaluates the features of its convertible pre ferred stock to determine if the features require bifurcation from the underlying shares by evaluating whether they are clearly and closely related to the underlying shares and if they do, or do not, meet the definition of a derivative. Income taxes The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of events that have been included in the Company’s financial statements and tax returns. Deferred tax assets and liabilities are determined based upon the differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities and for loss and credit carryforwards, using enacted tax rates expected to be in effect in the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that these assets may not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible. The Company recognizes and measures uncertain tax positions using a two-step approach set forth in authoritative guidance. The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, none of the benefit attributable to the position is recognized. The tax benefit to be recognized for any tax position that meets the more-likely-than-not recognition threshold is calculated as the largest amount that is more than 50 % likely of being realized upon resolution of the contingency. Judgment is required to evaluate uncertain tax positions. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on a number of factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of the audit, and effective settlement of audit issues. The Company’s policy is to include penalties and interest expense related to income taxes as a component of income taxes expense, as necessary. The Company has not reported any interest or penalties associated with income tax since inception. The Inflation Reduction Act of 2022 (the “Act”) was signed into U.S. law on August 16, 2022. The Act includes various tax provisions, including an excise tax on stock repurchases, expanded tax credits for clean energy incentives, and a corporate alternative minimum tax that generally applies to U.S. corporations with average adjusted financial statement income over a three year period in excess of $ 1 billion. The Company does not expect the Act to materially impact its financial statements. The Tax Cuts and Jobs Act (TCJA) requires taxpayers to capitalize and amortize research and experimental (R&D) expenditures under section 174 for tax years beginning after December 31, 2021. This rule became effective for the Company during the year ended December 31, 2022. The Company will amortize these costs for tax purposes over 5 years if the R&D was performed in the U.S. and over 15 years if the R&D was performed outside the U.S. Stock-based compensation The Company maintains an equity incentive plan as a long-term incentive for employees, consultants, and directors. We generally issue new common shares upon exercise of options and vesting of RSUs. The Company accounts for all stock-based awards granted to employees 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 measurement date for stock awards, including stock options and restricted stock units (RSUs) is the date of grant. Awards granted by the Company are routine in nature including new hire, annual, and promotional grants that are not designed to be spring-loaded, and therefore the market price is not adjusted when estimating the grant-date fair value of these awards. From time to time, the Company may grant stock options to employees, including executive officers, and consultants that vest upon the satisfaction of service-based, performance-based or market-based vesting conditions. For awards that vest based on multiple conditions, the Company estimates the fair value on its grant date using the Black-Scholes option valuation model or the Monte Carlo Simulation valuation model, depending on the terms and conditions of the particular award. • For awards where vesting occurs based on a service condition only, the Company recognizes compensation expense using the straight-line method over the requisite service period. • For awards where vesting occurs based on either a service condition or a performance condition, the Company recognizes stock-based compensation over the requisite service period using the accelerated attribution method for awards with a performance condition if the performance condition is deemed probable of being met. • For awards where vesting occurs based on either a service condition or a market condition, compensation expense is recognized over the requisite service period. If the market condition is satisfied prior to the completion of the requisite service period, any remaining unrecognized compensation expense will be accelerated at that time. The Company does not reverse compensation expense associated with these awards if the market condition is not met. The Company recognizes stock-based compensation expense for the portion of awards that have vested. Forfeitures are accounted for as they occur. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes options-pricing model, which requires inputs based on certain subjective assumptions, including the expected stock price volatility, the expected term of the option, the risk-free interest rate for a period that approximates the expected term of the option, and the Company’s expected dividend yield. The fair value of each restricted stock unit is determined based on the number of shares granted and the value of the Company’s common stock on the date of grant. The fair value of the Company’s common stock prior to the Company’s IPO was determined by the Board with the assistance of management. The fair value of common stock was determined using valuation methodologies which utilize certain assumptions including probability weighting of events, volatility, time to an exit event, a risk-free interest rate and an assumption for a discount for lack of marketability. In determining the fair value of common stock, the methodologies used to estimate the enterprise value of the Company were performed using methodologies, approaches, and assumptions consistent with the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. Net loss per share attributable to common stockholders Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration of potential dilutive securities. The Series 1 convertible preferred stock are participating securities but because they do not have the obligation to share in the loss of the Company, are excluded from the calculation of basic net loss per share. Stock options, unvested RSUs, Series 1 convertible preferred stock, and shares estimated to be purchased under the Company’s employee stock purchase plan (ESPP) are considered potentially dilutive common stock. The Company computes diluted net loss per share after giving consideration to all potentially dilutive common stock outstanding during the period, determined using the treasury-stock and if-converted methods, except where the effect of including such securities would be antidilutive. For the years ended December 31, 2022 and 2021, the Company reported a net loss. The potentially dilutive common stock would have been anti-dilutive and therefore basic and diluted loss per share attributable to common stockholders were the same. Comprehensive loss Comprehensive loss is defined as the change in equity of a business enterprise during a period |