CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)	Aug. 31, 2021	May 31, 2021
Current Assets:
Cash and cash equivalents	$ 4,996,623	$ 4,199,311
Accounts receivable, less allowance for doubtful accounts of $742,524 and $837,415 as of August 31, 2021 and May 31, 2021, respectively	772,190	1,455,051
Inventories, net	2,861,779	3,206,255
Prepaid expenses and other	315,221	370,290
Total current assets	8,945,813	9,230,907
Property and equipment, net of accumulated depreciation and amortization of $2,000,167 and $1,972,357 as of August 31, 2021 and May 31, 2021, respectively	287,852	310,520
Right of use assets, net of accumulated amortization of $531,974 and $469,077 as of August 31, 2021 and May 31, 2021, respectively	1,490,184	1,553,081
Investments	165,324	165,324
Intangible assets, net of accumulated amortization of $83,683 and $126,769 as of August 31, 2021 and May 31, 2021, respectively	360,292	294,830
Other assets	266,582	264,151
Total Assets	11,516,047	11,818,813
Current Liabilities:
Accounts payable and accrued expenses	641,404	583,380
Accrued compensation	507,722	388,896
Lease liability, current portion	332,967	327,944
Total current liabilities	1,482,093	1,300,220
Lease liability, net of current portion	1,230,898	1,291,570
Total Liabilities	2,712,991	2,591,790
Commitments and contingencies (Notes 1 and 6)
Shareholders' Equity:
Preferred stock, Series A 5% convertible, $0.08 par value, 571,429 shares authorized, none issued and outstanding as of August 31, 2021 and May 31, 2021
Preferred stock, undesignated, no par value, 4,428,571 shares authorized, none issued and outstanding as of August 31, 2021 and May 31, 2021
Common stock, $0.08 par value, 25,000,000 shares authorized, 12,510,210 and 12,307,157 issued and outstanding at August 31, 2021 and May 31, 2021, respectively	1,000,815	984,571
Additional paid-in-capital	39,944,726	38,836,743
Accumulated other comprehensive loss	(53,569)	(47,956)
Accumulated deficit	(32,088,916)	(30,546,335)
Total Shareholders' Equity	8,803,056	9,227,023
Total Liabilities and Shareholders' Equity	11,516,047	11,818,813
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, none issued and outstanding as of August 31, 2021 and May 31, 2021
Preferred stock, undesignated, no par value, 4,428,571 shares authorized, none issued and outstanding as of August 31, 2021 and May 31, 2021