Note 7 - Equity Incentive Plan - Stock Option Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Shares underlying outstanding awards (in shares)	3,180,882
Shares underlying outstanding awards, weighted average exercise price (in dollars per share)	$ 0.38
Shares underlying outstanding awards, weighted average remaining contractual term (Year)	5 years 5 months 19 days	5 years 3 months 18 days
Granted (in shares)	130,000
Granted, weighted average exercise price (in dollars per share)	$ 2.00
Exercised (in shares)	(12,702)
Exercised, weighted average exercise price (in dollars per share)	$ 0.41
Shares underlying outstanding awards (in shares)	3,298,180	3,180,882
Shares underlying outstanding awards, weighted average exercise price (in dollars per share)	$ 0.44	$ 0.38
Exercisable options (in shares)	2,690,983
Exercisable options, weighted average exercise price (in dollars per share)	$ 0.34
Exercisable options, weighted average remaining contractual term (Year)	4 years 9 months 29 days