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Note 7 - Patents (Details Textual) - USD ($)
3 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Amortization of Intangible Assets $ 13,426 $ 11,352
Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year 40,000  
Finite-Lived Intangible Asset, Expected Amortization, Year One 52,000  
Finite-Lived Intangible Asset, Expected Amortization, Year Two 34,000  
Finite-Lived Intangible Asset, Expected Amortization, Year Three 28,000  
Finite-Lived Intangible Asset, Expected Amortization, after Year Three 110,000  
Patents [Member]    
Amortization of Intangible Assets $ 13,000 $ 11,000
Patents [Member] | Minimum [Member]    
Finite-Lived Intangible Asset, Useful Life (Year) 3 years  
Patents [Member] | Maximum [Member]    
Finite-Lived Intangible Asset, Useful Life (Year) 20 years