Note 13 - Subsequent Events (Details Textual) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 13, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Proceeds from Issuance of Common Stock				$ 1,497,000	$ 3,267,000
Lincoln Park Capital Fund, LLC [Member]
Stock Issued During Period, Shares, New Issues (in shares)		1,190,223	2,440,958	2,833,846	4,353,919
Proceeds from Issuance of Common Stock		$ 203,000	$ 485,000	$ 502,000	$ 903,000
Subsequent Event [Member] | Lincoln Park Capital Fund, LLC [Member]
Stock Issued During Period, Shares, New Issues (in shares)	873,788
Proceeds from Issuance of Common Stock	$ 142,000