Note 9 - Equity Transactions (Details Textual) - USD ($)			1 Months Ended		12 Months Ended
	Dec. 29, 2022	Nov. 19, 2021	Mar. 31, 2021	Jan. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Jun. 24, 2021	Dec. 08, 2020
Common Stock, Shares Authorized (in shares)					20,000,000	20,000,000	20,000,000	10,000,000
Shares Issued, Value, Share-Based Payment Arrangement, before Forfeiture					$ 15,750	$ 396,306
Stock Issued During Period, Value, Issued for Services					$ 143,763
Class of Warrant or Right, Exercised During Period (in shares)					(0)	1,599,204
Common Stock, Par or Stated Value Per Share (in dollars per share)					$ 0.0001	$ 0.0001
November 2021 Public Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)		1,950,000
Shares Issued, Price Per Share (in dollars per share)		$ 6.00
Proceeds from Issuance or Sale of Equity, Total		$ 11,700,000
Underwriting Discounts and Commissions, Percent		7.00%
Payments of Stock Issuance Costs		$ 927,000
Registered Direct Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)	930,000
Shares Issued, Price Per Share (in dollars per share)	$ 1.61
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.0001
Warrants Issued in Connection with December 2020 Public Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)						1,599,204
Proceeds from Warrant Exercises						$ 7,991,101
Warrants Exercised in Net Share Settlement [Member]
Class of Warrant or Right, Exercised During Period (in shares)			9,436
Stock Issued During Period, Shares, Warrants Exercised (in shares)			2,913
Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	1,678,696
Class of Warrant or Right, Purchase Price of Warrants or Rights (in dollars per share)	$ 1.6099
Series A-1 Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	2,608,696
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 1.36
Warrants and Rights Outstanding, Term (Year)	5 years
Series A-2 Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	2,608,696
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 1.36
Warrants and Rights Outstanding, Term (Year)	3 years
Warrants to Purchase Units Sold in May 2016 Private Placement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)					4,800
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 25.00
Warrants and Rights Outstanding, Term (Year)					7 years
Warrants to Purchase Units Sold in February 2017 Private Placement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)					1,641
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 35.00
Warrants to Purchase Units Sold in October 2017 Private Placement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)					2,400
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 25.00
Warrants to Purchase Units Sold in May 2016, February 2017 and October 2017 Private Placement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)					17,682
Warrants and Rights Outstanding					$ 474,870
Share-Based Payment Arrangement, Nonemployee [Member]
Stock Issued During Period, Shares, Issued for Services (in shares)				10,000
Stock Issued During Period, Value, Issued for Services				$ 50,300		50,300
Employee [Member]
Share-Based Payment Arrangement, Expense					$ 15,750	$ 124,998
Shares Issued, Shares, Share-Based Payment Arrangement, before Forfeiture (in shares)				53,938	7,500	17,053
Shares Issued, Value, Share-Based Payment Arrangement, before Forfeiture				$ 271,308
Scientific Advisory Board [Member]
Shares Issued, Shares, Share-Based Payment Arrangement, before Forfeiture (in shares)					5,000
Shares Issued, Value, Share-Based Payment Arrangement, before Forfeiture					$ 10,500
Board Members [Member]
Shares Issued, Shares, Share-Based Payment Arrangement, before Forfeiture (in shares)					65,479	11,327
Shares Issued, Value, Share-Based Payment Arrangement, before Forfeiture					$ 133,263	$ 41,004