Note 8 - Stockholders' Equity (Details Textual) - USD ($)					12 Months Ended
	Dec. 31, 2022	Dec. 16, 2022	Apr. 12, 2022	Mar. 29, 2021	Dec. 31, 2022	Dec. 31, 2021
Proceeds from Issuance of Common Stock					$ 5,540,000	$ 2,001,000
Payments of Stock Issuance Costs					$ 418,000	$ 59,000
Underwriters [Member]
Stock Issued During Period, Shares, New Issues				80,000
Purchase Agreement with Lincoln Park [Member]
Sale of Stock, Aggregate Value, Maximum				$ 20,000,000
Stock Issued During Period, Shares, New Issues				373,832
Shares Issued, Price Per Share				$ 5.35
Proceeds from Issuance of Common Stock				$ 2,000,000
Stock Issuable, Commitment Shares on Pro Rata Basis					5,000
Sales Agreement with Cantor Fitzgerald Co (Cantor) [Member]
Sale of Stock, Aggregate Value, Maximum	$ 8,500,000		$ 10,500,000
Stock Issued During Period, Shares, New Issues					711,511
Proceeds from Issuance of Common Stock					$ 1,803,000
Accrued Sales Commission, Current, Percentage			3.00%
Payments of Stock Issuance Costs					$ 256,000
Private Placement [Member] | Qualified Institutional Buyers and Institutional Accredited Investors [Member]
Stock Issued During Period, Shares, New Issues		2,122,017
Shares Issued, Price Per Share		$ 1.68
Proceeds from Issuance of Common Stock		$ 3,400,000
Payments of Stock Issuance Costs		$ 162,000
Private Placement [Member] | Company’s Directors and Executive Officers [Member]
Stock Issued During Period, Shares, New Issues		499,997