Condensed consolidated statements of cash flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Cash flows from operating activities:
Net loss	$ (23,121)	$ (25,900)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	1,658	1,634
Loss on fixed asset impairment	19	0
Stock-based compensation expense	2,260	2,256
Provision for excess and obsolete inventory	441	95
Noncash lease expense	609	609
Accretion on investments	149	(890)
Other	17	18
Changes in operating assets and liabilities:
Accounts receivable	1,471	521
Inventory	(1,119)	(1,564)
Prepaid expenses and other current assets	182	502
Other long-term assets	0	1
Accounts payable	800	207
Accrued expenses and other current liabilities	(1,668)	(2,586)
Deferred revenue	(463)	(547)
Net cash used in operating activities	(18,765)	(25,644)
Cash flows from investing activities:
Purchases of property and equipment	(685)	(1,044)
Purchases of investments	(2,290)	(4,368)
Maturity of investments	23,000	43,744
Net cash provided by investing activities	20,025	38,332
Cash flows from financing activities:
Proceeds from issuance of Class A common stock - stock option exercise	423	0
Proceeds from issuance of Class A common stock - employee stock purchase plan	90	168
Tax withholding on settlement of restricted stock units	(418)	0
Payments on finance lease obligations	(14)	(20)
Net cash provided by financing activities	81	148
Net decrease in cash, cash equivalents and restricted cash	1,341	12,836
Cash, cash equivalents and restricted cash at beginning of period	17,276	24,569
Cash, cash equivalents and restricted cash at end of period	18,617	37,405
Supplemental disclosure of cash flow information
Cash paid for interest	24	17
Supplemental disclosure of non-cash investing activities
Purchases of property and equipment in accounts payable and accrued expenses	$ 75	$ 277