CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net loss	$ (11,031)	$ (10,206)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	220	182
Change in fair value of warrants	0	957
Loan forgiveness income	0	(333)
Loss on disposal of fixed assets	0	206
Expense for 401(k) company common stock match	112	109
Stock-based compensation	1,675	739
Noncash lease expense	358	429
Deferred tax asset	35	56
Changes in operating assets and liabilities:
Accounts receivable	(78)	(14)
Unbilled receivables	(7)	(7)
Prepaid expenses and other assets	63	(69)
Accounts payable	23	(219)
Accrued expenses	(160)	99
Other liabilities	(6)	13
Lease liabilities	(457)	(601)
Net cash used in operating activities	(9,253)	(8,659)
Cash flows from investing activities
Purchase of property and equipment	(189)	(76)
Proceeds from sale of property and equipment	0	10
Purchase of investments	(10,639)	(9,279)
Proceeds from sale and maturity of short-term investments	6,250	8,700
Net cash used in investing activities	(4,578)	(645)
Cash flows from financing activities
Proceeds from warrants exercised	3,856	1,658
Proceeds from PPP loan	0	333
Proceeds from securities offerings, net of issuance costs	11,993	5,305
Taxes paid on employees' behalf related to vesting of stock awards	(103)	(17)
Net cash provided in financing activities	15,746	7,279
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(9)	(37)
Net increase (decrease) in cash, cash equivalents and restricted cash	1,906	(2,062)
Cash, cash equivalents and restricted cash at beginning of year	3,687	5,749
Cash, cash equivalents and restricted cash at end of year	5,593	3,687
Supplemental Cash Flow Disclosure:
Interest paid	$ 9	$ 8