Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019		Apr. 01, 2019
Accounts Receivable, Credit Loss Expense (Reversal)	$ 0	$ 0
Product Warranty Term (Year)	1 year
Impairment of Long-Lived Assets Held-for-use	$ 0	0
Depreciation, Depletion and Amortization, Nonproduction, Total	364,409	498,813
Operating Lease, Liability, Total	833,734
Operating Lease, Right-of-Use Asset	$ 816,358		[1]
Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability, Total				$ 298,983
Operating Lease, Right-of-Use Asset				$ 261,644
Machinery and Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years

[1] The March 31, 2019 Balance Sheet is derived from the audited financial statements contained in our Annual Report on Form 10-K for the fiscal year ended March 31, 2019.