Note 7 - Stockholders' Equity - Warrant Activity (Details) - $ / shares	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Balance at December 31, 2022 (in shares)	340,689
Balance at December 31, 2022 (in dollars per share)	$ 19.40
Balance at December 31, 2022 (Year)	2 years 6 months 21 days	1 year 10 months 24 days
Warrants granted (in shares)	1,071,429
Warrants exercised (in shares)	(158,731)
Exercisable and Outstanding at March 31, 2023 (in shares)	2,199,816
Exercisable and Outstanding at March 31, 2023 (in dollars per share)	$ 3.84
Pre-funded Warrant [Member]
Warrants granted (in shares)	946,429