Note 5 - Share-based Compensation - Stock Options (Details) - USD ($)		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Options outstanding, Granted (in shares)		0
2018 Equity Incentive Plan [Member]
Options outstanding, balance (in shares)		41,108,448	28,484,549
Weighted average exercise price, balance (in dollars per share)		$ 0.19	$ 0.19
Options outstanding, Granted (in shares)		1,547,938	1,320,498
Weighted average exercise price, Granted (in dollars per share)		$ 0.3	$ 0.2
Weighted average remaining term, Outstanding (Year)		7 years 4 months 24 days	7 years 6 months
Aggregate intrinsic Value, Balance		$ 5,909,000	$ 678,000	[1]
Options outstanding, balance (in shares)		42,656,386	29,805,047
Weighted average exercise price, balance (in dollars per share)		$ 0.19	$ 0.19
Unvested (in shares)		(5,025,052)
Weighted average exercise price per share, unvested (in dollars per share)		$ 0.2
Options outstanding, Vested (in shares)		37,631,334
Weighted average exercise price, Vested (in dollars per share)		$ 0.19
Weighted average remaining term, Vested (Year)		7 years 4 months 24 days
Aggregate intrinsic value, Vested	[1]	$ 4,455,000
The 2007 Equity Incentive Plan [Member]
Options outstanding, balance (in shares)		1,564,085	1,904,085
Weighted average remaining term, Outstanding (Year)		10 months 24 days	1 year 6 months
Options outstanding, balance (in shares)		1,564,085	1,904,085
Options outstanding, Expired (in shares)		0	0
The 2007 Equity Incentive Plan [Member] | Minimum [Member]
Weighted average exercise price, balance (in dollars per share)		$ 0.61	$ 0.56
Weighted average exercise price, balance (in dollars per share)		0.61	0.56
Weighted average exercise price per share, Expired (in dollars per share)		$ 0	$ 0
Non Plan [Member]
Options outstanding, balance (in shares)		17,375,044	19,023,829
Weighted average exercise price, balance (in dollars per share)		$ 0.39	$ 0.39
Options outstanding, Granted (in shares)			48,804
Weighted average exercise price, Granted (in dollars per share)			$ 0.2
Weighted average remaining term, Outstanding (Year)		3 years 1 month 6 days	4 years 1 month 6 days
Options outstanding, balance (in shares)		17,099,668	19,072,633
Weighted average exercise price, balance (in dollars per share)		$ 0.39	$ 0.39
Unvested (in shares)		(1,056,177)
Weighted average exercise price per share, unvested (in dollars per share)		$ 0.26
Options outstanding, Vested (in shares)		16,043,491
Weighted average exercise price, Vested (in dollars per share)		$ 0.4
Weighted average remaining term, Vested (Year)		3 years 1 month 6 days
Aggregate intrinsic value, Vested		$ 437,000
Options outstanding, Expired (in shares)		(275,376)
Weighted average exercise price per share, Expired (in dollars per share)		$ 0.44
Aggregate intrinsic value, balance		$ 695,000	$ 88,000	[1]

[1] Aggregate intrinsic value based on closing common stock price of $0.35 at March 31, 2024.