Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating activities:
Net loss	$ (2,396)	$ (2,635)
Adjustments to reconcile net loss to cash used in operating activities:
Amortization of finance lease right-of-use asset	0	19
Amortization of marketable securities premiums	0	16
Stock-based compensation expense	85	181
Change in fair value of warrant liability	63	0
Change in operating assets and liabilities:
Prepaid expenses and other current assets	(62)	39
Accounts payable	(448)	315
Accrued expenses	642	(225)
Cash used in operating activities	(2,116)	(2,290)
Investing activities:
Sale of marketable securities	0	1,154
Cash provided by investing activities	0	1,154
Financing activities:
Payment of finance lease liability	0	(23)
Cash used in financing activities	0	(23)
Net decrease in cash and cash equivalents	(2,116)	(1,159)
Cash and cash equivalents, at beginning of period	3,781	3,702
Cash and cash equivalents, at end of period	$ 1,665	$ 2,543