Note 17 - Preferred Stock and Warrants (Details Textual)											12 Months Ended
	Mar. 11, 2020 USD ($) $ / shares shares	Nov. 08, 2019 USD ($) $ / shares shares	Nov. 07, 2019 shares	Mar. 28, 2018 USD ($) $ / shares shares	May 14, 2015 shares	Feb. 23, 2015 USD ($) $ / shares shares	Feb. 23, 2015 USD ($) $ / shares shares	Jul. 08, 2013 USD ($) $ / shares shares	Feb. 19, 2013 USD ($) $ / shares shares	Nov. 10, 2011 USD ($) $ / shares shares	Mar. 28, 2020 USD ($) shares	Mar. 30, 2019 USD ($) $ / shares shares	Mar. 31, 2018 shares	Feb. 16, 2015 $ / shares shares
Proceeds from Issuance of Common Stock	$ 510,000	$ 2,100,000									$ 2,564,000	$ 1,192,000
Proceeds from Warrant Exercises											$ 211,000	$ 112,000
Stock Issued During Period, Shares, New Issues (in shares) | shares	146,668	699,333
Shares Issued, Price Per Share (in dollars per share) | $ / shares	$ 3.75	$ 3.75
Conversion of Series E Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Issued (in shares) | shares		896,636	896,636
Conversion of Stock, Shares Converted (in shares) | shares		88,600	88,600
Alara Capital AVI II, LLC [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares								1,017,405
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares								$ 1.43
Class of Warrant Or Right Exercised in Period					14,587
Shares Issued Upon Cashless Warrant Exercise (in shares) | shares					7,216
New Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares								511,186
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares								$ 1.43
Series E Preferred Stock Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares				14,867								6.67
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares				$ 3.75								$ 3.75
Class of Warrant or Right, Number of Securities Called by Warrants or Rights, Percentage of Common Shares Into Which the Preferred Shares Can Be Converted				5.00%								5.00%
Series B Preferred Stock [Member]
Proceeds from Issuance of Preferred Stock, Preference Stock, and Warrants, Total										$ 2,199,000
Preferred Stock, Shares Issued, Total (in shares) | shares										9,997	9,997	9,997
Sale of Stock, Price Per Share (in dollars per share) | $ / shares										$ 220
Preferred Stock, Value, Issued, Ending Balance												$ 2,000,000
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs												$ 202,000
Series C Preferred Stock [Member]
Preferred Stock, Shares Issued, Total (in shares) | shares									3,424.65		3,424.65	3,424.65
Sale of Stock, Price Per Share (in dollars per share) | $ / shares									$ 146
Preferred Stock, Value, Issued, Ending Balance									$ 457,000
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs									43,000
Proceeds from Issuance of Preferred Stock and Preference Stock									$ 500,000
Series D Preferred Stock [Member]
Preferred Stock, Shares Issued, Total (in shares) | shares								5,111.86			5,111.86	5,111.86
Proceeds from Issuance of Convertible Preferred Stock								$ 858,000
Series D Preferred Stock [Member] | SPA [Member]
Payments of Stock Issuance Costs								41,000
Debt Instrument, Convertible, Beneficial Conversion Feature								238,000
Series D Preferred Stock [Member] | SPA [Member] | Unallocated [Member]
Proceeds from Issuance of Convertible Preferred Stock								817,000
Series D Preferred Stock [Member] | SPA [Member] | Allocated [Member]
Proceeds from Issuance of Convertible Preferred Stock								498,000
Proceeds from Issuance of Common Stock								$ 360,000
Debt Instrument, Convertible, Conversion Price (in dollars per share) | $ / shares								$ 0.97
Series B, C, and D Preferred Stock [Member]
Preferred Stock, Value, Issued, Ending Balance											$ 2,745,000	$ 2,911,000
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares													100
Series C and D Warrants [Member] | Alara Capital AVI II, LLC [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares						1,002,818	1,002,818
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares						$ 1.43	$ 1.43
Payments of Stock Issuance Costs						$ 42,000
Proceeds from Warrant Exercises						$ 1,434,000
New Warrant [Member] | Alara Capital AVI II, LLC [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares						194,437	194,437							898,634
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares						$ 1.76	$ 1.76							$ 1.78
Number of Warrants Sold (in shares) | shares						2	2
Warrant Purchase Price							$ 137,000
Warrant Purchase Price Per Share (in dollars per share) | $ / shares							$ 0.125
Warrant Term (Year)						5 years
Additional Warrant [Member] | Alara Capital AVI II, LLC [Member]
Class of Warrant or Right, Outstanding (in shares) | shares						14,587	14,587
Series E Preferred Stock [Member]
Preferred Stock, Shares Issued, Total (in shares) | shares											100,000	100,000
Preferred Stock, Value, Issued, Ending Balance											$ 177,000	$ 1,895,000
Proceeds from Issuance of Preferred Stock and Preference Stock				$ 1,095,000								1,405,000
Payments of Stock Issuance Costs				$ 57,000								$ 212,000
Stock Issued During Period, Shares, New Issues (in shares) | shares				42,800							0	56,200
Preferred Stock, Dividend Rate, Percentage				6.00%
Issuance of Stock, Number of Investors				15
Shares Issued, Price Per Share (in dollars per share) | $ / shares				$ 25								$ 25
Proceeds from Issuance of Preferred Stock and Preference Stock, Net of Issuance Costs				$ 1,000,000								$ 1,200,000
Stock Issued During Period, Placement Agent Fees, Percentage of Gross Proceeds				5.00%								5.00%
Series E Preferred Stock [Member] | Placement Agent [Member]
Payments of Stock Issuance Costs												$ 56,875