Note 4 - Intangible Assets - Intangible Assets (Details) - USD ($)	Sep. 30, 2025	Mar. 31, 2025	Sep. 30, 2024
Cost	$ 50,309	$ 50,309
Accumulated amortization	38,707	35,242
Net carrying amount	11,602	15,067
Accumulated amortization	(38,707)	(35,242)
Intangible assets, net of accumulated amortization of $38,707 and $35,242 at September 30, 2025 and March 31, 2025, respectively	11,602	15,067
Patents And Trademarks [Member]
Cost	35,794	35,794
Accumulated amortization	29,027	27,982
Net carrying amount	6,767	7,812
Accumulated amortization	(29,027)	(27,982)
Intangible assets, net of accumulated amortization of $38,707 and $35,242 at September 30, 2025 and March 31, 2025, respectively	$ 6,767	$ 7,812
Patents And Trademarks [Member] | Minimum [Member]
Finite-Lived Intangible Assets, Useful Life (Year)	10 years		10 years
Patents And Trademarks [Member] | Maximum [Member]
Finite-Lived Intangible Assets, Useful Life (Year)	15 years	15 years
Software [Member]
Cost	$ 14,515	$ 14,515
Finite-Lived Intangible Assets, Useful Life (Year)	3 years		3 years
Accumulated amortization	$ 9,680	7,260
Net carrying amount	4,835	7,255
Accumulated amortization	(9,680)	(7,260)
Intangible assets, net of accumulated amortization of $38,707 and $35,242 at September 30, 2025 and March 31, 2025, respectively	$ 4,835	$ 7,255