Condensed Consolidated Statements of Stockholders' Equity (Current Period Unaudited) - USD ($)	Total	Common Stock [Member]	Preferred Stock [Member] Convertible Preferred Stock	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Treasury Stock, Common [Member]
Balance (in shares) at Dec. 31, 2022		126,624,110	582
Balance at Dec. 31, 2022	$ 117,964,000	$ 22,792,000	$ 0	$ 251,366,000	$ (156,194,000)	$ 0
Stock-based compensation	1,573,000	0	0	1,573,000	0	0
Net loss	(6,281,000)	$ 0	$ 0	0	(6,281,000)	0
Balance (in shares) at Mar. 31, 2023		126,624,110	582
Balance at Mar. 31, 2023	113,256,000	$ 22,792,000	$ 0	252,939,000	(162,475,000)	0
Balance (in shares) at Dec. 31, 2023		125,304,064	582
Balance at Dec. 31, 2023	91,016,000	$ 22,792,000	$ 0	255,987,000	(186,288,000)	(1,475,000)
Stock-based compensation	417,000	0	0	417,000	0	0
Issuance of common stock upon warrant exercise	204,000	$ 37,000	0	167,000	0	0
Issuance of common stock upon warrant exercise, shares		203,750
Net loss	(5,878,000)	$ 0	$ 0	0	(5,878,000)	0
Balance (in shares) at Mar. 31, 2024		125,507,814	582
Balance at Mar. 31, 2024	$ 85,759,000	$ 22,829,000	$ 0	$ 256,571,000	$ (192,166,000)	$ (1,475,000)