Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities
Net loss	$ (5,347)	$ (4,086)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation	160	100
Non-cash lease expense	7	33
Stock-based compensation	2,655	2,514
Accretion and short-term investment discount	(197)
Changes in operating assets and liabilities:
Accounts receivable	216	713
Inventories	(97)	(417)
Prepaid expenses and other current assets	(7)	478
Other assets	24	25
Accounts payable	563	(871)
Accrued liabilities	(1,547)	(561)
Deferred revenue	768	(104)
Other liabilities		(17)
Net cash used in operating activities	(2,802)	(2,193)
Cash flows from investing activities
Purchase of property and equipment	(349)	(1,154)
Net cash used in investing activities	(349)	(1,154)
Cash flows from financing activities
Proceeds from issuance of stock, net of issuance costs	56	54
Net cash provided by financing activities	56	54
Net decrease in cash, cash equivalents, and restricted cash	(3,095)	(3,293)
Cash, cash equivalents, and restricted cash at beginning of period	9,855	40,144
Cash, cash equivalents, and restricted cash at end of period	6,760	36,851
Supplemental disclosure of cash flow information:
Purchase of property and equipment included in accounts payable	15	699
Reconciliation of cash, cash equivalents, and restricted cash to balance sheet as of March 31st:
Cash and cash equivalents	5,623	35,095
Restricted cash - current	525	618
Restricted cash	612	1,138
Total cash, cash equivalents, and restricted cash	$ 6,760	$ 36,851