Note 9 - Equity Transactions - Summary of Warrants Outstanding, Exercise Price, and Expiration Dates (Details) - $ / shares	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Warrants Issued (in shares)	2,045,846	2,048,186	3,662,661
Warrants Expiring in June 2023 [Member]
Exercise Price (in dollars per share)	$ 55
Warrants Issued (in shares)	1,000
Warrants Expiring in June 2023, Two [Member]
Exercise Price (in dollars per share)	$ 25
Warrants Issued (in shares)	84,800
Warrants Expiring in February 2024 [Member]
Exercise Price (in dollars per share)	$ 35
Warrants Issued (in shares)	60,837
Warrants Expiring in October 2024 [Member]
Exercise Price (in dollars per share)	$ 25
Warrants Issued (in shares)	2,400
Warrants Expiring in October 2024, Two [Member]
Exercise Price (in dollars per share)	$ 25
Warrants Issued (in shares)	57,600
Warrants Expiring in November 2024 [Member]
Exercise Price (in dollars per share)	$ 9.37
Warrants Issued (in shares)	302,379
Warrants Expiring in April 23, 2025 [Member]
Exercise Price (in dollars per share)	$ 25
Warrants Issued (in shares)	80,000
Warrants Expiring in December, 2025 [Member]
Exercise Price (in dollars per share)	$ 65
Warrants Issued (in shares)	35,200
Warrants Expiring in September 2025 [Member]
Exercise Price (in dollars per share)	$ 11
Warrants Issued (in shares)	2,223
Warrants Expiring in September 2027 [Member]
Exercise Price (in dollars per share)	$ 15
Warrants Issued (in shares)	283,111
Warrant Expiring in December 2025, Two [Member]
Exercise Price (in dollars per share)	$ 5
Warrants Issued (in shares)	1,078,796
Warrants Expiring in December 2025, Third [Member]
Exercise Price (in dollars per share)	$ 6.25
Warrants Issued (in shares)	57,500