Note 7 - Stockholders' Equity - Warrant Activity (Details) - $ / shares	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Mar. 15, 2023	Dec. 31, 2022
Balance, shares (in shares)		340,689
Balance, exercise price (in dollars per share)		$ 19.40
Balance, term (Year)	4 years 9 months 25 days	4 years 9 months 25 days		1 year 10 months 24 days
Warrants granted, shares (in shares)		1,071,429
Warrants expired (in shares)		(14,518)
Warrants exercised (in shares)		(158,731)
Exercisable, shares (in shares)	1,238,869	1,238,869
Balance, exercise price (in dollars per share)	$ 3.14	$ 3.14
Pre-funded Warrant [Member]
Balance, term (Year)			5 years 6 months
Warrants granted, shares (in shares)		946,429
Warrants exercised (in shares)	(946,429)	(946,429)