Note 10 - Stockholders' Equity (Details Textual) - USD ($)				12 Months Ended
	Feb. 14, 2023	Jan. 14, 2022	Feb. 14, 2018	Dec. 31, 2022	Dec. 31, 2021	Aug. 31, 2022	Aug. 04, 2022	Feb. 16, 2018
Preferred Stock, Shares Authorized				5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share				$ 0.001	$ 0.001
Preferred Stock, Shares Issued				60,961	56,451
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				60,961	56,451
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				8,255,148	132,265
Preferred Stock Redemption Discount				$ 5,111,000	$ (0)
Common Stock, Shares Authorized				100,000,000	100,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)				$ 0.001	$ 0.001
Common Stock, Shares, Issued (in shares)				7,832,644	4,778,263
Common Stock, Shares, Outstanding, Ending Balance (in shares)				7,832,644	4,778,263
Class of Warrant or Right, Outstanding				51,185,758	26,456,895
Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input		5.5
Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input		1.3661
Measurement Input, Discount Rate [Member]
Warrants and Rights Outstanding, Measurement Input		0.0151
Measurement Input, Expected Dividend Rate [Member]
Warrants and Rights Outstanding, Measurement Input		0
Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		807,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 9.60
Warrants and Rights Outstanding, Term		5 years
Common Stock Warrants, Issued with Series D Convertible Preferred Stock [Member]
Proceeds from Issuance of Warrants		$ 3,600,000
Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		66,500		66,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 10.00		$ 10.00
Warrants and Rights Outstanding, Term		5 years
Class of Warrant or Right, Outstanding				1,330,000
Registered Direct Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							784,019
Stock Issued During Period, Shares, Warrants Exercised				784,019
Private Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,369,864
Private Pre-funded Warrants [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, Warrants Exercised	747,864
Class of Warrant or Right, Outstanding	622,000
Class of Warrant or Right, Exercised (in shares)	747,864
Pre-funded Warrants Issued in August 2022 Financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				1,369,864
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 0.0001			$ 0.0001
Class of Warrant or Right, Outstanding				1,369,864
Series A Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						2,853,883
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 1.502
Warrants and Rights Outstanding, Term						5 years 6 months
Series B Financing Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						2,853,883
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 1.502
Warrants and Rights Outstanding, Term						2 years
Placement Agent Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						171,233
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 2.19
Warrants and Rights Outstanding, Term						5 years
January 2022 Public Offering [Member]
Proceeds from Issuance of Convertible Preferred Stock		$ 4.0
Conversion of Series B Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted					93
Conversion of Stock, Shares Issued					18,600
Conversion of Series D Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted				7,600
Conversion of Stock, Shares Issued				950,000
Series A Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				60,876	56,366
Preferred Stock, Liquidation Preference Per Share				$ 1,000
Preferred Stock, Convertible, Conversion Price				$ 400
Dividends, Preferred Stock, Total				$ 4,500,000	$ 4,200,000
Series A Preferred Stock [Member] | CRG [Member]
Preferred Stock Dividends, Shares				4,510	4,175
Series A Preferred Stock [Member] | Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Preferred Stock, Dividend Rate, Percentage			8.00%
Series B Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share								$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				85	85
Preferred Stock, Convertible, Conversion Price				$ 1.502	$ 1.502
Series D Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share		$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				0
Series D Preferred Stock [Member] | Common Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 9.60
Warrants and Rights Outstanding, Term		5 years
Class of Warrant or Right, Outstanding		807,500
Series D Preferred Stock [Member] | Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		66,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 10.00
Warrants and Rights Outstanding, Term		5 years
Series D Preferred Stock [Member] | January 2022 offering [Member]
Preferred Stock, Par or Stated Value Per Share		$ 0.001
Preferred Stock, Convertible, Conversion Price		$ 8.00
Stock Issued During Period, Shares, New Issues		7,600
Shares Issued, Price Per Share (in dollars per share)		$ 1,000
Preferred Stock, Convertible, Shares Issuable		950,000
Series D Preferred Stock [Member] | January 2022 offering [Member] | Common Warrants [Member]
Conversion of Warrants Allowed Maximum Ownership of Common Stock Percentage		4.99%
Conversion of Warrants Allowed Maximum Ownership of Common Stock Percentage upon Election		9.99%
Series D Preferred Stock [Member] | January 2022 Public Offering [Member]
Preferred Stock, Par or Stated Value Per Share		$ 1,000
Preferred Stock, Convertible, Conversion Price		$ 8.00
Stock Issued During Period, Shares, New Issues		7,600