Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating Activities
Net loss	$ (20,209)	$ (14,525)
Adjustments to reconcile net loss to cash flows from operating activities:
Depreciation and amortization	362	372
Stock-based compensation expense	670	862
Change in fair value of warrant liability	(758)	(11,827)
Financing expense	3,483	9,247
Net realized and unrealized gains on marketable securities	(65)	124
Changes in operating assets and liabilities:
Accounts receivable	(545)	(656)
Inventory	697	140
Other current assets	(65)	(68)
Other assets and liabilities	(7)	(96)
Accounts payable and accrued expenses	(1,500)	1,278
Net cash used in operating activities	(17,937)	(15,149)
Investing Activities:
Additions to intangible assets	(99)	0
Proceeds from sales of marketable securities	578	14,850
Purchase of property and equipment	(149)	(122)
Net cash provided by investing activities	330	14,728
Financing Activities:
Proceeds from public stock offerings, net	2,109	9,449
Proceeds from Series J Preferred Stock and Warrants	1,482	0
Proceeds from the exercise of warrants	120	0
Payments on finance lease liability	(28)	(26)
Net cash provided by financing activities	3,683	9,423
Effect of exchange rate changes on cash	(13)	(7)
Net decrease in cash and cash equivalents	(13,937)	8,995
Cash and cash equivalents - beginning of year	17,737	8,742
Cash and cash equivalents - end of year	3,800	17,737
Supplemental schedule of non-cash activities
Inventory transferred to property, plant and equipment	41	42
Issuance of Common Stock for exercise of Series I Warrants	7,623	0
Issuance of Series J Preferred Stock for exercise of Warrants	2,927	0
Deemed dividend on Series J Preferred Stock	2,297	0
Series J Preferred Stock issued for payment in kind dividend	121	0
Supplemental cash flow information
Cash paid for income taxes	$ 12	$ 9