Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating Activities
Net loss	$ (414)	$ (998)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	79	94
Amortization	11	14
Non-cash interest income on held-to-maturity securities	(95)	0
Provision for doubtful accounts, net of recoveries	0	(25)
Stock-based compensation, net of forfeitures	89	18
Changes in operating assets and liabilities:
Accounts receivable	990	(1,520)
Inventories	(116)	(13)
Prepaid expenses, other current assets and other non-current assets	51	(3)
Accounts payable	934	682
Accrued liabilities and other non-current liabilities	(519)	5
Net cash provided by (used in) operating activities	1,010	(1,746)
Investing Activities
Purchases of equipment and patents	(30)	(53)
Purchases of debt securities	(9,685)	0
Maturities of debt securities	1,000	0
Net cash used in investing activities	(8,715)	(53)
Financing Activities
Taxes paid on behalf of equity award participants	0	(17)
Net cash used in financing activities	0	(17)
Effect of exchange rate fluctuations on cash	75	2
Net decrease in cash, cash equivalents and restricted cash	(7,630)	(1,814)
Cash, cash equivalents, and restricted cash and cash equivalents at beginning of period (Note 2)	23,328	37,054
Cash, cash equivalents and restricted cash at end of period (Note 2)	$ 15,698	$ 35,240