Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating Activities
Net income (loss)	$ 281	$ (414)
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Depreciation	80	79
Amortization	16	11
Non-cash interest income on held-to-maturity securities	(9)	(95)
Stock-based compensation, net of forfeitures	104	89
Changes in operating assets and liabilities:
Accounts receivable	1,250	990
Employee retention credit receivable	(1,677)	0
Inventory	(99)	(116)
Prepaid expenses, other current assets and other non-current assets	151	51
Accounts payable	(563)	934
Accrued liabilities and other non-current liabilities	(609)	(519)
Net cash (used in) provided by operating activities	(1,075)	1,010
Investing Activities
Purchases of equipment and patents	(114)	(30)
Purchases of debt securities	(7,641)	(9,685)
Maturities of debt securities	2,750	1,000
Net cash used in investing activities	(5,005)	(8,715)
Financing Activities
Net cash provided by financing activities	0	0
Effect of exchange rate fluctuations on cash	(116)	75
Net decrease in cash and cash equivalents	(6,196)	(7,630)
Cash and cash equivalents at beginning of period	17,578	23,328
Cash and cash equivalents at end of period	$ 11,382	$ 15,698