Note 3 - Summary of Significant Accounting Policies (Details) - Disaggregation of Revenue - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Commercial Customers [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 182,987	$ 280,056	$ 478,910	$ 612,431
U.S. Government [Member]
Disaggregation of Revenue [Line Items]
Revenues	3,140,454	1,284,099	5,644,594	2,376,681
Test Units [Member] | Commercial Customers [Member]
Disaggregation of Revenue [Line Items]
Revenues	182,987	280,056	478,910	612,431
Test Units [Member] | U.S. Government [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 3,140,454	$ 1,284,099	$ 5,644,594	$ 2,376,681