Note 5 - Intangible Assets (Tables)

3 Months Ended

Jun. 30, 2021

Notes Tables

Schedule of Finite-Lived Intangible Assets [Table Text Block]

	June 30, 2021										March 31, 2021
	Cost		Weighted Average Amortization Period (Years)			Accumulated Amortization			Net Carrying Amount		Cost		Weighted Average Amortization Period (Years)			Accumulated Amortization			Net Carrying Amount
Patents & Trademarks	$	35,794	10	-	15	$	(17,591	)	$	18,203	$	35,794	10	-	15	$	(16,871	)	$	18,923

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

For the twelve months ended June 30,
2022	$	2,882
2023		2,882
2024		2,882
2025		2,275
2026		2,371
Thereafter		4,911
	$	18,203