Quarterly report pursuant to Section 13 or 15(d)

Note 4 - Stock-based Compensation - Summary of Stock Option Activity (Details)

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Note 4 - Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($)
 9 Months Ended 12 Months Ended
Sep. 30, 2021
Dec. 31, 2020
Outstanding at beginning of period (in shares) 549,970  
Outstanding at beginning of period, weighted average exercise price (in dollars per share) $ 8.81  
Outstanding, weighted average remaining contractual life (Year) 7 years 7 months 6 days 8 years
Outstanding, aggregate intrinsic value $ 128,765 $ 209,280
Granted (in shares) 234,500  
Granted, weighted average exercise price (in dollars per share) $ 2.53  
Exercised (in shares) (2,000)  
Exercised, weighted average exercise price (in dollars per share) $ 1.06  
Cancelled/Forfeited (in shares) (67,600)  
Cancelled/Forfeited, weighted average exercise price (in dollars per share) $ 4.01  
Expired (in shares) (2,090)  
Expired, weighted average exercise price (in dollars per share) $ 61.75  
Outstanding at end of period (in shares) 712,780 549,970
Outstanding at end of period, weighted average exercise price (in dollars per share) $ 7.07 $ 8.81
Exercisable at end of period (in shares) 222,882  
Exercisable at end of period, weighted average exercise price (in dollars per share) $ 13.27  
Exercisable, weighted average remaining contractual life (Year) 5 years 7 months 6 days  
Exercisable, aggregate intrinsic value $ 47,381