Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (34,759)	$ (32,537)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, amortization and write-off of property and equipment	1,370	1,531
Amortization and write-off of intangibles	678	771
Amortization of right of use assets under operating leases	493	470
Amortization of net premiums (discounts) on marketable securities	650	204
Gain on extinguishment of note payable	(5,032)
Stock-based compensation	11,936	9,115
Changes in operating assets and liabilities:
Trade accounts receivable	(2,647)	114
Other current assets	(119)	259
Other assets	(83)	(8)
Accounts payable and other accrued liabilities	2,078	512
Deferred revenue	(10)	(199)
Lease liability and other long-term liabilities	(671)	(170)
Net cash used in operating activities	(26,116)	(19,938)
Cash flows from investing activities:
Loan to related party	(2,000)
Purchase of property and equipment	(966)	(1,020)
Capitalized patent costs	(606)	(612)
Maturities of marketable securities	82,076	42,951
Purchases of marketable securities	(52,523)	(75,583)
Net cash provided by (used in) investing activities	25,981	(34,264)
Cash flows from financing activities:
Issuance of common stock, net of issuance costs		38,603
Issuance of preferred stock, net of issuance costs		16,888
Exercise of stock options		5,922
Proceeds from note payable		5,032
Purchase of common stock	(5,772)	(3,760)
Net cash provided by (used in) financing activities	(5,772)	62,685
Net increase (decrease) in cash and cash equivalents	(5,907)	8,483
Cash and cash equivalents at beginning of period	19,696	11,213
Cash and cash equivalents at end of period	13,789	19,696
Supplemental disclosure of cash flow information:
Cash received (paid) for income taxes, net	(40)	20
Supplemental schedule of non-cash investing and financing activities:
Property and equipment and patent costs in accounts payable	(58)	76
Stock-based compensation capitalized to software and patent costs	136	158
Cashless exercise of stock options	$ 6,007
Beneficial conversion feature		11,443
Series B preferred stock dividend, converted into common stock		$ 248