Note 6 - Shareholders' Equity - Stock Option Activity (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares
Balance, number of shares (in shares) | shares	1,664,014
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 2.07
Balance, weighted average remaining contractual life (Year)	6 years 6 months 10 days	6 years 7 months 20 days
Balance, aggregate intrinsic value | $	$ 91,690	$ 405,223
Granted, number of shares (in shares) | shares	66,500
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 1.76
Exercised, number of shares (in shares) | shares	(59,375)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 1.18
Forfeited, number of shares (in shares) | shares	(62,479)
Forfeited, weighted average exercise price (in dollars per share) | $ / shares	$ 1.80
Expired, number of shares (in shares) | shares	(44,500)
Expired, weighted average exercise price (in dollars per share) | $ / shares	$ 3.47
Balance, number of shares (in shares) | shares	1,564,160	1,664,014
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 2.06	$ 2.07
Vested and expected to vest, number of shares (in shares) | shares	1,521,640
Vested and expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 2.07
Vested and expected to vest, weighted average remaining contractual life (Year)	6 years 5 months 23 days
Vested and expected to vest, aggregate intrinsic value | $	$ 88,659
Exercisable, number of shares (in shares) | shares	1,049,454
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 2.31
Exercisable, weighted average remaining contractual life (Year)	5 years 10 months 28 days
Exercisable, aggregate intrinsic value | $	$ 50,904