CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)	Feb. 28, 2021	May 31, 2020
Current Assets:
Cash and cash equivalents	$ 5,272,565	$ 8,641,027
Accounts receivable, less allowance for doubtful accounts of $649,419 and $70,981 as of February 28, 2021 and May 31, 2020, respectively	1,878,124	1,765,871
Inventories, net	2,860,055	2,850,836
Prepaid expenses and other	774,117	1,509,083
Total current assets	10,784,861	14,766,817
Property and equipment, net of accumulated depreciation and amortization of $1,945,908 and $1,867,643 as of February 28, 2021 and May 31, 2020, respectively	307,873	279,379
Right of use assets, net of accumulated amortization of $405,407 and $231,489 as of February 28, 2021 and May 31, 2020, respectively	1,537,591	1,711,510
Investments	165,324	165,324
Intangible assets, net of accumulated amortization of $517,792 and $496,124 as of February 28, 2021 and May 31, 2020, respectively	269,252	168,655
Other assets	282,857	168,193
Total Assets	13,347,758	17,259,878
Current Liabilities:
Accounts payable and accrued expenses	756,136	986,711
Accrued compensation	366,936	278,627
Lease liability, current portion	228,936	211,809
Total current liabilities	1,352,008	1,477,147
Lease liability, net of current portion	1,396,167	1,569,678
Total Liabilities	2,748,175	3,046,825
Commitments and contingencies (Notes 5 and 6)
Shareholders' Equity:
Preferred stock, Series A 5% convertible, $0.08 par value, 571,429 shares authorized, none issued and outstanding at February 28, 2021 and 321,429 issued and outstanding at May 31, 2020 and Preferred stock, undesignated, no par value, 4,428,571 shares authorized, none issued and outstanding at February 28, 2021 and May 31, 2020		25,714
Common stock, $0.08 par value, 25,000,000 shares authorized, 12,302,157 and 11,740,089 issued and outstanding at February 28, 2021 and May 31, 2020, respectively	984,170	939,205
Additional paid-in-capital	36,563,562	35,213,707
Accumulated other comprehensive loss	(48,528)	(39,841)
Accumulated deficit	(26,899,621)	(21,925,732)
Total Shareholders' Equity	10,599,583	14,213,053
Total Liabilities and Shareholders' Equity	13,347,758	17,259,878
5% Percent Convertible Preferred Stock [Member] | Series A Preferred Stock [Member]
Shareholders' Equity:
Preferred stock, Series A 5% convertible, $0.08 par value, 571,429 shares authorized, none issued and outstanding at February 28, 2021 and 321,429 issued and outstanding at May 31, 2020 and Preferred stock, undesignated, no par value, 4,428,571 shares authorized, none issued and outstanding at February 28, 2021 and May 31, 2020		25,714
Preferred Stock [Member]
Shareholders' Equity:
Preferred stock, Series A 5% convertible, $0.08 par value, 571,429 shares authorized, none issued and outstanding at February 28, 2021 and 321,429 issued and outstanding at May 31, 2020 and Preferred stock, undesignated, no par value, 4,428,571 shares authorized, none issued and outstanding at February 28, 2021 and May 31, 2020