Quarterly report pursuant to Section 13 or 15(d)

Note 12 - Summary of Stock Options - Summary of Option Activity Under All Plans (Details)

v3.20.2
Note 12 - Summary of Stock Options - Summary of Option Activity Under All Plans (Details)
6 Months Ended 12 Months Ended
Jun. 30, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
shares
Options outstanding, beginning of period (in shares) | shares 10,087,678  
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares $ 2.22  
Options outstanding, weighted average remaining contractual term (Year) 9 years 146 days 9 years 328 days
Options outstanding, aggregate intrinsic value | $ $ 3,928,715
Options granted (in shares) | shares 468,000  
Options granted, weighted average exercise price (in dollars per share) | $ / shares $ 0.88  
Options exercised (in shares) | shares  
Options exercised, weighted average exercise price (in dollars per share) | $ / shares  
Options canceled (in shares) | shares (532,237)  
Options canceled, weighted average exercise price (in dollars per share) | $ / shares $ 5.81  
Options outstanding, end of period (in shares) | shares 10,023,441 10,087,678
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares $ 1.97 $ 2.22
Vested and exercisable and expected to vest, end of period (in shares) | shares 9,164,577  
Vested and exercisable and expected to vest, end of period, weighted average exercise price (in dollars per share) | $ / shares $ 2.06  
Vested and exercisable and expected to vest, end of period, weighted average remaining contractual term (Year) 9 years 146 days  
Vested and exercisable and expected to vest, end of period, aggregate intrinsic value | $  
Vested and exercisable, end of period (in shares) | shares 1,447,596  
Vested and exercisable, end of period, weighted average exercise price (in dollars per share) | $ / shares $ 6.41  
Vested and exercisable, end of period, weighted average remaining contractual term (Year) 9 years 36 days  
Vested and exercisable, end of period, aggregate intrinsic value | $