Note 9 - Equity (Details Textual) - USD ($)				1 Months Ended				3 Months Ended	6 Months Ended	9 Months Ended
	Aug. 30, 2021	Aug. 01, 2021	Sep. 28, 2020	Jul. 30, 2021	May 31, 2021	Jul. 31, 2020	May 31, 2020	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Apr. 30, 2021	Apr. 21, 2021	Dec. 31, 2020	Sep. 27, 2020	Jun. 09, 2020	Jun. 08, 2020	Dec. 31, 2019	Sep. 15, 2017
Common and Preferred Stock, Shares Authorized (in shares)																350,000,000	179,000,000
Common Stock, Shares Authorized (in shares)			1,000,000,000.0					2,000,000,000	2,000,000,000	2,000,000,000			2,000,000,000.0	2,000,000,000		345,000,000
Preferred Stock, Shares Authorized (in shares)								5,000,000	5,000,000	5,000,000				5,000,000		5,000,000
Common Stock, Shares, Issued, Total (in shares)								347,200,961	347,200,961	347,200,961				180,096,317
Common Stock, Shares, Outstanding, Ending Balance (in shares)								347,194,257	347,194,257	347,194,257				180,089,613
Proceeds from Issuance of Common Stock										$ 100,000	$ 2,296,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)								3,904,470	3,904,470	3,904,470
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)								$ 0.10	$ 0.10	$ 0.10				$ 0.17
Class of Warrant or Right, Outstanding (in shares)								3,150,000	3,150,000	3,150,000				753,775
Warrants and Rights Outstanding								$ 0	$ 0	$ 0
Warrants or Rights, Issued During Period (in shares)										3,000,000
Warrants or Rights, Cancelled During Period (in shares)										603,375
Warrants or Rights, Exercised During Period (in shares)										400
Warrants or Rights Exercised During Period, Exercise Price (in dollars per share)										$ 0.01
Warrants Expiring April 15, 2028 [Member]
Class of Warrant or Right, Outstanding (in shares)								600,000	600,000	600,000
Warrants Expiring Three Years From Initial Vesting [Member]
Class of Warrant or Right, Outstanding (in shares)								150,000	150,000	150,000
Warrants Expiring July 11, 2028 [Member]
Class of Warrant or Right, Outstanding (in shares)								400,000	400,000	400,000
Warrants Expiring August 3, 2028 [Member]
Class of Warrant or Right, Outstanding (in shares)								200,000	200,000	200,000
Warrants Expiring August 4, 2026 [Member]
Class of Warrant or Right, Outstanding (in shares)								1,800,000	1,800,000	1,800,000
Director Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)												200,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)												$ 0.07
Warrants and Rights Outstanding, Term (Year)												1 year
Warrants, Vesting Expense								$ 15,636		$ 25,636
Director Warrants [Member] | Chief Financial Officer [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 0.06
Warrants or Rights, Issued During Period (in shares)				400,000
Director Warrants [Member] | Advisory Board Member [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 0.07	$ 0.048
Warrants or Rights, Issued During Period (in shares)	1,800,000	200,000
Minimum [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)								$ 0.01	$ 0.01	$ 0.01
Maximum [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)								$ 0.80	$ 0.80	$ 0.80
Lincoln Park [Member]
Sale of Stock, Number of Shares Issued in Transaction (in shares)					1,000,000		2,500,000	0	1,000,000	1,000,000
Shares Issued, Price Per Share (in dollars per share)								$ 0.10	$ 0.10	$ 0.10
Proceeds from Issuance of Common Stock										$ 100,000
Deferred Offering Costs					$ 70,000		$ 400,000	$ 70,000	$ 70,000	$ 70,000
Exchange of Series A Preferred Stock for Series A-1 Preferred Stock [Member]
Conversion of Stock, Shares Converted (in shares)						18,828
Conversion of Series A Preferred to Common Stock [Member]
Conversion of Stock, Shares Converted (in shares)								2,330		14,911
Conversion of Stock, Shares Issued (in shares)								11,647,000		74,562,000
Conversion of Series A-1 Preferred to Common Stock [Member]
Conversion of Stock, Shares Converted (in shares)								2,239		14,782
Conversion of Stock, Shares Issued (in shares)								11,194,000		73,910,000
Series A Preferred Stock [Member]
Preferred Stock, Shares Authorized (in shares)								38,000	38,000	38,000				38,000					38,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)								$ 0.01	$ 0.01	$ 0.01				$ 0.01					$ 0.01
Preferred Stock, Shares Outstanding, Ending Balance (in shares)								0	0	0				14,911				37,467
Common Stock Rate Exhange From Preferred Stock, Per Month			10.00%
Preferred Stock, Convertible, Conversion Price (in dollars per share)			$ 0.20												$ 1.15
Preferred Stock, Dividend Rate, Percentage			8.00%
Preferred Stock, Dividend Rate, Percentage, Stock			10.00%
Preferred Stock, Dividend Rate, Percentage, Liquidiation Preference			4.00%
Dividends Payable								$ 0	$ 0	$ 0				$ 0
Preferred Stock Dividends, Shares (in shares)								109,836		1,789,587
Series A-1 Preferred Stock [Member]
Preferred Stock, Shares Authorized (in shares)						31,021		38,000	38,000	38,000				38,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)								$ 0.01	$ 0.01	$ 0.01				$ 0.01
Preferred Stock, Shares Outstanding, Ending Balance (in shares)								0	0	0				14,782
Dividends Payable, Current						$ 1,849,000
Preferred Stock, Dividend Rate, Percentage						8.00%
Preferred Stock, Dividend Rate, Percentage, Stock						10.00%
Preferred Stock Dividends, Shares (in shares)								105,343		1,789,587
Preferred Stock, Liquidation Preference Per Share (in dollars per share)						$ 1,000
Preferred Stock, Liquidation Preference, Per Share, Percent						115.00%
Series B Preferred Stock [Member]
Preferred Stock, Shares Authorized (in shares)								750,000	750,000	750,000				750,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)								$ 0.01	$ 0.01	$ 0.01				$ 0.01
Preferred Stock, Shares Outstanding, Ending Balance (in shares)								239,400	239,400	239,400				239,400
Conversion of Stock, Shares Converted (in shares)									0
Dividends Payable								$ 8,000	$ 8,000	$ 8,000