Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 14,045,000	$ 19,162,000
Accounts receivable, net of allowance for doubtful accounts of $37 and $66 as of March 31, 2022 and December 31, 2021, respectively	509,000	549,000
Inventory	1,552,000	1,472,000
Prepaid expenses and other current assets	1,393,000	1,055,000
Total current assets	17,499,000	22,238,000
Property and equipment, net	1,351,000	1,554,000
Investment in unconsolidated limited liability company	455,000	577,000
Other assets	1,379,000	1,544,000
Total assets	20,684,000	25,913,000
Current liabilities:
Accounts payable	1,602,000	1,480,000
Accrued liabilities	3,376,000	3,053,000
Note payable, current portion	5,285,000	0
Total current liabilities	10,263,000	4,533,000
Note payable, noncurrent portion	0	5,124,000
Other noncurrent liabilities	265,000	1,190,000
Total liabilities	10,528,000	10,847,000
Commitments and contingences (Note 9)
Stockholders’ equity:
Common stock, $0.0001 par value; 75,000,000 shares authorized as of March 31, 2022 and December 31, 2021; 10,640,537 and 10,619,846 shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively	1,000	1,000
Additional paid-in capital	257,894,000	256,918,000
Accumulated deficit	(247,739,000)	(241,853,000)
Total stockholders’ equity	10,156,000	15,066,000
Total liabilities and stockholders’ equity	20,684,000	25,913,000
Series B Preferred Stock [Member]
Stockholders’ equity:
Convertible preferred stock	0	0
Series C Preferred Stock [Member]
Stockholders’ equity:
Convertible preferred stock		$ 0