Note 3 - Sale of Stock for Cash (Details Textual)	3 Months Ended
	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($) shares	Dec. 13, 2022 USD ($)
Proceeds from Issuance of Common Stock	$ 488,000	$ 800,000
Warrants Issued with 2020 Unit Offering [Member] | Minimum [Member]
Warrants and Rights Outstanding, Term (Year)	6 years
Warrants Issued with 2020 Unit Offering [Member] | Maximum [Member]
Warrants and Rights Outstanding, Term (Year)	5 years
The 2020 Unit Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares) | shares	1,394,173	3,656,000
Proceeds From Issuance of Common Stock, Gross	$ 267,000	$ 695,000
Proceeds from Issuance of Common Stock	$ 228,000
Number of Accredited Investors	5	11
Lincoln Park Capital Fund, LLC [Member]
Stock Purchase Agreement, Maximum Amount of Common Stock			$ 10,000,000
Stock Issued During Period, Shares, New Issues (in shares) | shares	766,175	545,402
Proceeds From Issuance of Common Stock, Gross	$ 260,000	$ 105,000