Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.2
Note 4 - Stock-based Compensation - Summary of Stock Option Activity (Details)
 6 Months Ended 12 Months Ended
Jun. 30, 2021
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Outstanding at beginning of period (in shares) | shares 549,970  
Outstanding at beginning of period, weighted average exercise price (in dollars per share) | $ / shares $ 8.81  
Outstanding, weighted average remaining contractual life (Year) 7 years 9 months 18 days 8 years
Outstanding, aggregate intrinsic value | $ $ 143,695 $ 209,280
Granted (in shares) | shares 232,000  
Granted, weighted average exercise price (in dollars per share) | $ / shares $ 2.54  
Exercised (in shares) | shares (2,000)  
Exercised, weighted average exercise price (in dollars per share) | $ / shares $ 1.06  
Cancelled/Forfeited (in shares) | shares (67,600)  
Cancelled/Forfeited, weighted average exercise price (in dollars per share) | $ / shares $ 4.01  
Outstanding at end of period (in shares) | shares 712,370 549,970
Outstanding at end of period, weighted average exercise price (in dollars per share) | $ / shares $ 7.25 $ 8.81
Exercisable at end of period (in shares) | shares 186,638  
Exercisable at end of period, weighted average exercise price (in dollars per share) | $ / shares $ 15.64  
Exercisable, weighted average remaining contractual life (Year) 5 years 3 months 18 days  
Exercisable, aggregate intrinsic value | $ $ 52,874