Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (9,801)	$ (17,273)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	135	160
Amortization of intangible assets	167	166
Stock-based compensation	896	2,007
Changes in operating assets and liabilities:
Accounts receivable	0	40
Inventory	0	(1,663)
Prepaid expenses and other current assets	160	191
Other receivables	(1)	(39)
Right-of-use assets	193	174
Accounts payable	587	609
Accrued expenses	496	215
Deferred revenue	4	0
Lease liabilities	(207)	(182)
Accrued interest on related party note payable	801	0
Accrued interest on note payable	0	1
Net cash used in operating activities	(6,570)	(15,594)
Cash flows from investing activities:
Purchases of property and equipment	(39)	(279)
Net cash used in investing activities	(39)	(279)
Cash flows from financing activities:
Proceeds from issuance of common stock under employee stock purchase plan	291	372
Proceeds from exercises of warrants	194	0
Payments made on insurance loan agreement	0	(437)
Payments made on related party note	(917)	0
Net cash used in financing activities	(432)	(65)
Net decrease in cash and cash equivalents	(7,041)	(15,938)
Cash and cash equivalents at beginning of period	61,139	28,614
Cash and cash equivalents at end of period	54,098	12,676
Supplemental disclosure of noncash investing and financing activities:
Equipment purchases included in accounts payable and accrued expenses	$ 0	$ (27)