Note 9 - Shareholders' Equity, Redeemable Convertible Preferred Stock, Options and Warrants (Details Textual)													1 Months Ended					12 Months Ended
	Sep. 05, 2023 USD ($) $ / shares shares	May 08, 2023 shares	Mar. 03, 2023 shares	Feb. 28, 2023 USD ($) $ / shares shares	May 31, 2022 USD ($) $ / shares shares	May 12, 2022 shares	Feb. 28, 2022 USD ($) $ / shares shares	Feb. 17, 2022 shares	Feb. 14, 2022 USD ($) $ / shares shares	May 12, 2017 USD ($) shares	Mar. 24, 2017 USD ($) $ / shares shares	Feb. 17, 2017 USD ($) $ / shares shares	Aug. 31, 2022 USD ($) shares	Mar. 31, 2022 USD ($) shares	Jul. 31, 2020 shares	Jul. 31, 2018 shares	Feb. 28, 2017 USD ($)	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Feb. 28, 2021 $ / shares	Sep. 30, 2004 shares
Class of Warrant or Right, Exercised (in shares)																		(0)	515,000
Class of Warrant or Right, Exercise Price, Exercised (in dollars per share) | $ / shares																		$ 0	$ 0.12
Class of Warrant or Right, Outstanding (in shares)																		0	0	7,065,000
Preferred Stock, Shares Authorized (in shares)																		5,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares																		$ 0.01
Share Price (in dollars per share) | $ / shares	$ 0.06			$ 0.04	$ 0.08													0.04			$ 0.09
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares																		$ 0	$ 0	$ 0.11
Share-Based Payment Arrangement, Expense | $																		$ 464,041	$ 352,458
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value | $																		$ 16,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)																		(0)	1,200,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)																		3,100,000	8,150,000
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares																		$ 0.04	$ 0.09
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price (in dollars per share) | $ / shares																		$ 0.05	$ 0.07	$ 0.06
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period (in shares)			1,000,000															3,306,000	1,734,000
Share-Based Payment Arrangement, Option [Member]
Share-Based Payment Arrangement, Expense | $																		$ 199,554	$ 280,393
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $																		$ 99,768
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)																		1 year 8 months 15 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested in Period, Fair Value | $																			$ 442,295
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum																			1.37%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum																			4.14%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate																			0.00%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum																			65.19%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum																			70.09%
Share-Based Payment Arrangement, Option [Member] | Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)																			5 years
Share-Based Payment Arrangement, Option [Member] | Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)																			7 years 6 months
Qualified Options [Member]
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares)													162,163	388,889
Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture (in shares)													37,837	611,111
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)													200,000	1,000,000				0
Share-Based Payment Arrangement, Expense, Tax Benefit | $													$ 0	$ 0
Qualified Options [Member] | Share-Based Payment Arrangement, Employee [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)																		3,100,000	1,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)																		5 years	5 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)																		10 years	10 years
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares																			$ 0.1
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested in Period, Fair Value | $																		$ 82,176
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum																		3.94%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum																		4.26%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate																		0.00%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum																		68.65%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum																		79.21%
Qualified Options [Member] | Share-Based Payment Arrangement, Employee [Member] | Share-Based Payment Arrangement, Tranche One [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)																			1 year
Qualified Options [Member] | Share-Based Payment Arrangement, Employee [Member] | Minimum [Member]
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares																		$ 0.04
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)																		5 years
Qualified Options [Member] | Share-Based Payment Arrangement, Employee [Member] | Maximum [Member]
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares																		$ 0.06
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)																		7 years
Restricted Stock Units (RSUs) [Member]
Share-Based Payment Arrangement, Expense | $																		$ 121,202	$ 0
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $																		$ 168,798
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)																		1 year 8 months 19 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			3 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Granted (in shares)			750,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)																		7,250,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)																		250,000
Chief Executive Officer [Member]
Employment Agreement, Minimum Price Per share (in dollars per share) | $ / shares				$ 0.05
One Employee [Member] | Qualified Options [Member] | Share-Based Payment Arrangement, Employee [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)																			25,000
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares																			$ 0.08
Two Employees [Member] | Qualified Options [Member] | Share-Based Payment Arrangement, Employee [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)																			125,000
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares																			$ 0.03
Executive Officer [Member] | Qualified Options [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)																			3,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)																			10 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price (in dollars per share) | $ / shares																			$ 0.09
Executive Officer [Member] | Qualified Options [Member] | Share-Based Payment Arrangement, Tranche One [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)																			2,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage																			50.00%
Executive Officer [Member] | Qualified Options [Member] | Share-Based Payment Arrangement, Tranche Two [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)																			1 year
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage																			50.00%
Director [Member] | Non-qualified Options [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)																			4,000,000
Executive Officers and Directors [Member] | Qualified Options [Member] | Share-Based Payment Arrangement, Tranche One [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage																			25.00%
Executive Officers and Directors [Member] | Qualified Options [Member] | Share-Based Payment Arrangement, Tranche Two [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage																			25.00%
President [Member] | Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)	2,500,000
Share-Based Payment Arrangement, Expense | $	$ 150,000
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares)	778,972
Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture (in shares)	1,721,028
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)		6,500,000
President [Member] | Restricted Stock Units (RSUs) [Member] | Share-Based Payment Arrangement, Tranche One [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)		1,500,000
President [Member] | Restricted Stock Units (RSUs) [Member] | Share-Based Payment Arrangement, Tranche Two [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)		2,000,000
President [Member] | Restricted Stock Units (RSUs) [Member] | Share-Based Payment Arrangement, Tranche Three [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)		3,000,000
Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares)																						2,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Percent of Gross Pay																						15.00%
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Additional Shares Authorized (in shares)															3,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)																		2,224,544
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)																		316,866	245,081
Stock Issued During Period, Value, Employee Stock Purchase Plan | $																		$ 8,398	$ 14,771
The 2015 Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares)																80,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Additional Shares Authorized (in shares)																20,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)																		20,292,546
The 2015 Incentive Plan [Member] | Chief Executive Officer [Member]
Shares Issued, Shares, Share-Based Payment Arrangement, before Forfeiture (in shares)				560,000			307,692
Shares Issued, Value, Share-Based Payment Arrangement, before Forfeiture | $				$ 28,000			$ 28,000
Shares Issued, Price Per Share (in dollars per share) | $ / shares				$ 0.05			$ 0.091
Employment Agreement, Minimum Price Per share (in dollars per share) | $ / shares							$ 0.05
Share-Based Payment Arrangement, Expense | $				$ 22,400			$ 27,692
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares)				216,440			120,461
Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture (in shares)				343,560			187,231
The 2006 Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)																11,089,967
Conversion of Convertible Debentures Into Series C Preferred Stock and Warrants [Member]
Preferred Stock, Shares Outstanding (in shares)																		630	630
Preferred Stock, Convertible, Conversion Price (in dollars per share) | $ / shares											$ 1,000
Proceeds from Issuance of Preferred Stock and Preference Stock | $											$ 675,947
Preferred Stock, Discount on Shares | $																		$ 0	$ 4,737
Preferred Stock, Value, Issued | $																		$ 630,000	$ 625,263
Debt Conversion, Converted Instrument, Warrants or Options Issued (in shares)										2,925,000	3,750
Debt Conversion, Original Debt, Amount | $										$ 780,000							$ 205,000
Debt Conversion, Converted Instrument, Shares Issued (in shares)										780
Convertible Debt [Member]
Debt Instrument, Interest Rate, Stated Percentage											8.00%
Repayments of Convertible Debt | $										$ 1,835,000
Subscription Agreements with Certain Investors [Member]
Proceeds from Issuance or Sale of Equity | $												$ 3,433,000
Conversion of Series B Preferred Stock Into Common Stock [Member]
Preferred Stock, Redemption Price Per Share (in dollars per share) | $ / shares					$ 1,000
Conversion of Stock, Shares Converted (in shares)					675															175
Conversion of Stock, Amount Issued | $					$ 675,000
Conversion of Stock, Shares Issued (in shares)					8,437,500
Conversion of Series C Preferred Stock Into Common Stock [Member]
Conversion of Stock, Shares Converted (in shares)																				150
Series B Preferred Stock [Member]
Preferred Stock, Shares Outstanding (in shares)																				675
Preferred Stock, Redemption Price Per Share (in dollars per share) | $ / shares																				$ 1,000
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount | $																				$ 675,000
Preferred Stock, Convertible, Conversion Price (in dollars per share) | $ / shares																				$ 2
Preferred Stock, Dividend Rate, Percentage																				0.00%
Series C Preferred Stock [Member]
Preferred Stock, Shares Outstanding (in shares)																		4,063	4,063
Preferred Stock, Redemption Price Per Share (in dollars per share) | $ / shares																		$ 1,000
Preferred Stock, Convertible, Conversion Price (in dollars per share) | $ / shares																		$ 0.1
Preferred Stock, Convertible, Threshold Trading Days																		90
Preferred Stock, Convertible, Stock Price Trigger (in dollars per share) | $ / shares																		$ 0.25
Dividends Payable | $				$ 243,780			$ 243,780
Stock Dividends, Shares (in shares)																		2,266,500	2,271,980
Dividends, Preferred Stock | $																		$ 90,660	$ 204,480
Payments of Dividends | $																		$ 153,120	$ 39,300
Series C Preferred Stock [Member] | Subscription Agreements with Certain Investors [Member]
Preferred Stock, Shares Outstanding (in shares)																		3,433
Preferred Stock, Dividend Rate, Percentage												6.00%
Stock Issued During Period, Shares, New Issues (in shares)												3,433
Proceeds from Issuance of Preferred Stock and Preference Stock | $												$ 2,895,379
Preferred Stock, Discount on Shares | $												13,440						$ 0
Stock Issued During Period, Value, New Issues | $												$ 3,419,560
Preferred Stock, Value, Issued | $																		$ 3,433,000
Class M Warrants [Member]
Class of Warrant or Right, Exercised (in shares)									515,000
Class of Warrant or Right, Exercise Price, Exercised (in dollars per share) | $ / shares									$ 0.12
Proceeds from Warrant Exercises | $									$ 61,800
Class of Warrants or Rights, Expirations (in shares)								3,625,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)												17,165,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares												$ 0.12
Proceeds from Issuance of Warrants | $												$ 537,621
Warrants and Rights Outstanding, Term (Year)												5 years
Class N Warrants [Member]
Class of Warrants or Rights, Expirations (in shares)						2,925,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares											$ 0.1
Proceeds from Issuance of Warrants | $											$ 104,053
Warrants and Rights Outstanding, Term (Year)											5 years