Condensed Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 23,078	$ 22,185
Accounts receivable, net of allowance for doubtful accounts of $6 at September 30, 2021 and $19 at December 31, 2020	1,400	1,484
Inventories	4,519	3,876
Prepaid expenses and other current assets	668	350
Total current assets	29,665	27,895
Right of use asset	3,408	4,063
Property and equipment, net	213	727
Other assets	452	510
Total assets	33,738	33,195
Current liabilities:
Accounts payable	1,178	694
Accrued compensation	1,379	1,703
Series A preferred stock dividends payable	3,132	0
Accrued expenses and other current liabilities	791	669
Leasehold liability, current portion	959	806
Borrowings, current portion	0	3,590
Total current liabilities	7,439	7,462
Borrowings, long-term portion	11,853	9,400
Leasehold liability, long-term portion	2,449	3,257
Other long-term liabilities	431	0
Total liabilities	22,172	20,119
Commitments and contingencies (Note 7)
Stockholders’ equity:
Convertible preferred stock issuable in series, par value of $0.001; Aggregate shares authorized: 5,000,000 at September 30, 2021 and December 31, 2020; Aggregate shares issued and outstanding: 52,276 and 52,369 at September 30, 2021 and December 31, 2020, respectively; aggregate liquidation preference of $52,191 at both September 30, 2021 and December 31, 2020 (Note 8)	0	0
Common stock, par value of $0.001; Shares authorized: 100,000,000 at September 30, 2021 and December 31, 2020; Shares issued and outstanding: 95,562,955 and 84,926,129 at September 30, 2021 and December 31, 2020, respectively	96	85
Additional paid-in capital	391,227	380,332
Accumulated deficit	(379,757)	(367,341)
Total stockholders’ equity	11,566	13,076
Total liabilities and stockholders’ equity	$ 33,738	$ 33,195