CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities
Net loss	$ (17,410)	$ (12,242)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	5,507	4,030
Depreciation and amortization	713	340
Accretion of discount on marketable securities	244	331
Amortization of debt issuance costs	51	88
Loss on sale and disposal of property and equipment	31	104
Changes in operating assets and liabilities:
Accounts receivable	1,603	581
Inventory	(3,178)	(1,725)
Prepaid expenses and other assets	12	20
Accounts payable	2,086	1,059
Accrued liabilities and other	(3,171)	(1,945)
Net cash used in operating activities	(13,512)	(9,359)
Cash flows from investing activities
Maturities of marketable securities	25,000	33,200
Purchases of marketable securities	(45,334)	(38,346)
Purchases of property and equipment	(2,274)	(1,976)
Net cash used in investing activities	(22,608)	(7,122)
Cash flows from financing activities
Proceeds from the exercise of stock options	169	601
Net cash provided by financing activities	169	601
Effect of exchange rate changes on cash and cash equivalents	(139)	(337)
Net decrease in cash and cash equivalents	(36,090)	(16,217)
Cash and cash equivalents at
Beginning of period	63,419	53,581
End of period	27,329	37,364
Supplemental disclosure of non-cash information
Vesting of early exercised stock options	0	9
Unpaid purchases of property and equipment	$ 241	$ 1,195