Note 6 - Stockholders' Equity - Warrants (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Outstanding (in shares)	4,268,221
Outstanding (in dollars per share)	$ 2.18
Outstanding (Year)	4 months 6 days	6 months
Issued, number of shares (in shares)	0
Issued, weighted average exercise price (in dollars per share)	$ 0
Exercised, number of shares (in shares)	0
Exercised, weighted average exercise price (in dollars per share)	$ 0
Expired or cancelled, number of shares (in shares)	(3,953,649)
Expired or cancelled, weighted average exercise price (in dollars per share)	$ 0
Outstanding (in shares)	314,572	4,268,221
Outstanding (in dollars per share)	$ 0.5	$ 2.18
Outstanding	$ 132,120