CONSOLIDATED BALANCE SHEETS - USD ($)	May 31, 2020	May 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 8,641,027	$ 686,785
Accounts receivable, less allowance for doubtful accounts of $70,981 and $73,110, respectively	1,765,871	1,454,652
Inventories, net	2,850,836	2,151,090
Prepaid expenses and other	1,509,083	202,402
Total current assets	14,766,817	4,494,929
PROPERTY AND EQUIPMENT:
Equipment	1,921,833	1,891,381
Furniture, fixtures and leasehold improvements	225,189	222,033
Total property and equipment	2,147,022	2,113,414
Accumulated depreciation	(1,867,643)	(1,762,344)
Net property and equipment	279,379	351,070
INTANGIBLE ASSETS, net of accumulated amortization	168,655	107,209
RIGHT OF USE ASSETS, net of accumulated amortization	1,711,510
INVESTMENTS	165,324	165,324
OTHER ASSETS	168,193	126,832
TOTAL ASSETS	17,259,878	5,245,364
CURRENT LIABILITIES:
Accounts payable and accrued expenses	986,711	1,037,565
Accrued compensation	278,627	226,829
Lease liability, current portion	211,809
Total current liabilities	1,477,147	1,264,394
Lease liability, net of current portion	1,569,678
Total liabilities	3,046,825	1,264,394
COMMITMENTS AND CONTINGENCIES (NOTE 8)
SHAREHOLDERS' EQUITY:
Preferred stock, Series A 5%, convertible, $0.08 par value, 571,429 shares authorized, 321,429 issued and outstanding at May 31, 2020 and no shares authorized, issued and outstanding at May 31, 2019 and Preferred stock, undesignated, no par value, authorized 4,428,571 and 5,000,000 shares, at May 31, 2020 and May 31, 2019, respectively and none issued and outstanding at May 31, 2020 and May 31, 2019	25,714
Common stock, $.08 par value; 25,000,000 shares authorized; 11,740,089 and 9,677,188 shares issued and outstanding at May 31, 2020 and 2019, respectively	939,205	774,173
Additional paid-in capital	35,213,707	22,830,006
Accumulated other comprehensive loss	(39,841)	(36,531)
Accumulated deficit	(21,925,732)	(19,586,678)
Total shareholders' equity	14,213,053	3,980,970
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	17,259,878	5,245,364
5% 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, 321,429 issued and outstanding at May 31, 2020 and no shares authorized, issued and outstanding at May 31, 2019 and Preferred stock, undesignated, no par value, authorized 4,428,571 and 5,000,000 shares, at May 31, 2020 and May 31, 2019, respectively and none issued and outstanding at May 31, 2020 and May 31, 2019	25,714
Preferred Stock [Member]
SHAREHOLDERS' EQUITY:
Preferred stock, Series A 5%, convertible, $0.08 par value, 571,429 shares authorized, 321,429 issued and outstanding at May 31, 2020 and no shares authorized, issued and outstanding at May 31, 2019 and Preferred stock, undesignated, no par value, authorized 4,428,571 and 5,000,000 shares, at May 31, 2020 and May 31, 2019, respectively and none issued and outstanding at May 31, 2020 and May 31, 2019