Note 9 - Stockholders' Equity - Options and Warrants Outstanding (Details) - shares	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)	4,381,348	3,758,670
Authorized for future Award grants under stockholder-approved stock-based incentive plans (in shares)	1,553,142
Warrants outstanding (in shares)	1,482,400
Total (in shares)	7,416,890

Number of warrants or rights outstanding.

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Aggregate number of common shares reserved for future issuance.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Number of shares authorized for issuance under share-based payment arrangement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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Number of options outstanding, including both vested and non-vested options.

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