Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities:
Net loss	$ (11,416)	$ (16,520)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of rights from Private Placement	180	0
Change in fair value of notes payable	17	542
Non-cash stock-based compensation	3,398	1,517
Non-cash operating lease expense	547	489
Depreciation and amortization	5	39
Common stock issued for services	155	62
Gain on extinguishments of debt, net	0	(259)
Non-cash interest expense	0	47
Gain on disposal of asset	(90)	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	176	(2,030)
Accounts payable	(2,302)	5,206
Accrued expenses and other current liabilities	(1,739)	881
Operating lease liability	(623)	(545)
Deferred revenue	(442)	(965)
Net cash used in operating activities	(12,134)	(11,536)
Investing activities:
Purchases of property and equipment	0	(15)
Proceeds from sale of property and equipment	331	0
Net cash provided by (used in) investing activities	331	(15)
Financing activities:
Proceeds from private placement	5,479	0
Proceeds from notes payable	0	5,620
Proceeds from issuance of common stock	752	1,556
Proceeds from exercise of warrants	20	70
Repayments of notes payable	0	(4,000)
Repayments of finance lease liabilities	(29)	(29)
Net cash provided by (used in) financing activities	6,222	3,217
Net change in cash and restricted cash	(5,581)	(8,334)
Cash and restricted cash at beginning of year	13,268	11,219
Cash and restricted cash at end of year	7,687	2,885
Components of cash and restricted cash:
Cash	7,562	2,810
Restricted cash	125	75
Total cash and restricted cash	7,687	2,885
Supplemental disclosure of cash flow information:
Cash paid for interest	36	1,007
Supplemental disclosure of noncash investing and financing activities:
Issuance of common stock upon extinguishment of notes payable and accrued interest	0	3,095
Withholding to cover taxes from RSU vesting	69	0
Finance lease liabilities arising from obtaining new right-of-use assets	0	41
Issuance of warrants to purchase common stock in connection with notes payable	$ 0	$ 47