Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating Activities
Net loss	$ (999)	$ (1,040)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	247	267
Amortization	46	70
Non-cash interest income on held-to-maturity securities	(319)	0
Provision for credit losses, net of recoveries	0	(45)
Stock-based compensation, net of forfeitures	288	136
Changes in operating assets and liabilities:
Accounts receivable	5	(3,449)
Inventories	68	(44)
Prepaid expenses, other current assets and other non-current assets	363	370
Accounts payable	172	1,094
Accrued liabilities and other non-current liabilities	520	50
Net cash provided by (used in) operating activities	391	(2,591)
Investing Activities
Purchases of equipment and patents	(201)	(186)
Purchases of debt securities	(14,026)	(9,777)
Maturities of debt securities	4,000	0
Net cash used in investing activities	(10,227)	(9,963)
Financing Activities
Proceeds from exercise of stock options	42	0
Taxes paid on behalf of equity award participants	0	(17)
Net cash provided by (used in) financing activities	42	(17)
Effect of exchange rate fluctuations on cash	(51)	(401)
Net decrease in cash and cash equivalents	(9,845)	(12,972)
Cash and cash equivalents at beginning of period	23,328	37,054
Cash and cash equivalents at end of period	$ 13,483	$ 24,082