Note 2 - Summary of Significant Accounting Policies - Stock Options, Valuation Assumptions (Details)	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022
Non Plan [Member]
Risk free interest rate	4.15%
Expected volatility	112.00%
Expected dividend yield	0.00%
Forfeiture rate	0.00%
Expected life in years (Year)	10 years
Non Plan [Member] \| Minimum [Member]
Risk free interest rate	2.32%
Expected volatility	115.00%
Non Plan [Member] \| Maximum [Member]
Risk free interest rate		3.83%
Expected volatility		117.00%
2018 Equity Incentive Plan [Member]
Expected dividend yield	0.00%	0.00%
Forfeiture rate	0.00%	0.00%
Expected life in years (Year)	10 years	10 years
2018 Equity Incentive Plan [Member] \| Minimum [Member]
Risk free interest rate	3.48%	2.32%
Expected volatility	112.00%	115.00%
2018 Equity Incentive Plan [Member] \| Maximum [Member]
Risk free interest rate	4.15%	3.83%
Expected volatility	114.00%	117.00%

Represents expected forfeiture rate for share-based payment awards.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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