RESTATEMENT OF PREVIOUSLY ISSUED FINANCIAL STATEMENTS (Details) - RESTATEMENT OF PREVIOUSLY ISSUED FINANCIAL STATEMENTS - USD ($)	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Feb. 28, 2021	Nov. 30, 2020	Aug. 31, 2020	Nov. 30, 2020	Feb. 28, 2021	May 31, 2021	May 31, 2020	May 31, 2019
Previously Reported [Member]
Shareholders' Equity:
Additional paid-in-capital	$ 36,563,562	$ 35,284,864	$ 35,231,415	$ 35,284,864	$ 36,563,562	$ 36,685,176	$ 35,213,707	$ 22,830,006
Accumulated deficit	(26,899,621)	(25,060,311)	(23,575,147)	(25,060,311)	(26,899,621)	(28,394,768)	(21,925,732)	(19,586,678)
Other Equity accounts			924,357	924,228	935,642	936,615	925,078	737,642
Total Shareholders' Equity	10,599,583	11,148,781	12,580,625	11,148,781	10,599,583	9,227,023	14,213,053	3,980,970
Cost of sales	3,667,143	1,011,030	960,930	1,971,960	5,639,103	6,702,046	4,910,935
Gross Profit (Loss)	(38,505)	361,496	182,876	544,372	505,867	496,981	1,781,776
Operating Expenses:
Selling, general and administrative	1,278,393	1,254,847	1,164,564	2,419,411	3,697,804	4,608,950	2,274,415
Research and development	563,216	586,403	674,693	1,261,096	1,824,312	2,410,506	1,910,209
Total operating expense	1,841,609	1,841,250	1,839,257	3,680,507	5,522,116	7,019,456	4,184,624
Loss from operations	(1,880,114)	(1,479,754)	(1,656,381)	(3,136,135)	(5,016,249)	(6,522,475)	(2,402,848)
Loss before income taxes	(1,842,427)	(1,471,771)	(1,648,290)	(3,120,061)	(4,962,488)	(6,455,979)	(2,331,664)
Net loss	$ (1,839,310)	$ (1,485,164)	$ (1,649,415)	$ (3,134,579)	$ (4,973,889)	$ (6,469,036)	$ (2,339,054)
Basic net loss per common share (in Dollars per share)	$ (0.15)	$ (0.13)	$ (0.14)	$ (0.27)	$ (0.42)	$ (0.54)	$ (0.23)
Diluted net loss per common share (in Dollars per share)	$ (0.15)	$ (0.13)	$ (0.14)	$ (0.27)	$ (0.42)	$ (0.54)	$ (0.23)
Comprehensive loss	$ (1,844,747)	$ (1,486,694)	$ (1,651,136)	$ (3,137,829)	$ (4,982,576)	$ (6,477,151)	$ (2,342,364)
Cash flows from operating activities:
Net loss	(1,839,310)	(1,485,164)	(1,649,415)	(3,134,579)	(4,973,889)	(6,469,036)	(2,339,054)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock option expense			3,808	24,227	261,176	377,391	200,470
Net cash used in operating activities			(1,597,146)	(2,880,218)	(4,244,064)	(5,251,748)	(4,297,498)
Cash and cash equivalents at end of year	5,272,565	5,683,787	6,964,314	5,683,787	5,272,565	4,199,311	8,641,027
Revision of Prior Period, Adjustment [Member]
Shareholders' Equity:
Additional paid-in-capital	1,935,493	1,650,262	1,417,328	1,650,262	1,935,493	2,151,567	1,174,349	836,232
Accumulated deficit	(1,935,493)	(1,650,262)	(1,417,328)	(1,650,262)	(1,935,493)	(2,151,567)	(1,174,349)	(836,232)
Other Equity accounts
Total Shareholders' Equity
Cost of sales	34,926	52,777	64,787	117,564	152,490	130,696	43,549
Gross Profit (Loss)	(34,926)	(52,777)	(64,787)	(117,564)	(152,490)	(130,696)	(43,549)
Operating Expenses:
Selling, general and administrative	249,554	149,999	141,380	291,379	540,933	785,575	272,207
Research and development	751	30,158	36,812	66,970	67,721	60,947	22,361
Total operating expense	250,305	180,157	178,192	358,349	608,654	846,522	294,568
Loss from operations	(285,231)	(232,934)	(242,979)	(475,913)	(761,144)	(977,218)	(338,117)
Loss before income taxes	(285,231)	(232,934)	(242,979)	(475,913)	(761,144)	(977,218)	(338,117)
Net loss	$ (285,231)	$ (232,934)	$ (242,979)	$ (475,913)	$ (761,144)	$ (977,218)	$ (338,117)
Basic net loss per common share (in Dollars per share)	$ (0.03)	$ (0.02)	$ (0.02)	$ (0.04)	$ (0.07)	$ (0.08)	$ (0.03)
Diluted net loss per common share (in Dollars per share)	$ (0.03)	$ (0.02)	$ (0.02)	$ (0.04)	$ (0.07)	$ (0.08)	$ (0.03)
Comprehensive loss	$ (285,231)	$ (232,934)	$ (242,979)	$ (475,913)	$ (761,144)	$ (977,218)	$ (338,117)
Cash flows from operating activities:
Net loss	(285,231)	(232,934)	(242,979)	(475,913)	(761,144)	(977,218)	(338,117)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock option expense			242,979	475,913	761,144	977,218	338,117
Net cash used in operating activities
Cash and cash equivalents at end of year
Restatement of the Company's Financial Statements [Member]
Shareholders' Equity:
Additional paid-in-capital	38,499,055	36,935,126	36,648,743	36,935,126	38,499,055	38,836,743	36,388,056	23,666,238
Accumulated deficit	(28,835,114)	(26,710,573)	(24,992,475)	(26,710,573)	(28,835,114)	(30,546,335)	(23,100,081)	(20,422,910)
Other Equity accounts			924,357	924,228	935,642	936,615	925,078	737,642
Total Shareholders' Equity	10,599,583	11,148,781	12,580,625	11,148,781	10,599,583	9,227,023	14,213,053	$ 3,980,970
Cost of sales	3,702,069	1,063,807	1,025,717	2,089,524	5,791,593	6,832,742	4,954,484
Gross Profit (Loss)	(73,431)	308,719	118,089	426,808	353,377	366,285	1,738,227
Operating Expenses:
Selling, general and administrative	1,527,947	1,404,846	1,305,944	2,710,790	4,238,737	5,394,525	2,546,622
Research and development	563,967	616,561	711,505	1,328,066	1,892,033	2,471,453	1,932,570
Total operating expense	2,091,914	2,021,407	2,017,449	4,038,856	6,130,770	7,865,978	4,479,192
Loss from operations	(2,165,345)	(1,712,688)	(1,899,360)	(3,612,048)	(5,777,393)	(7,499,693)	(2,740,965)
Loss before income taxes	(2,127,658)	(1,704,705)	(1,891,269)	(3,595,974)	(5,723,632)	(7,433,197)	(2,669,781)
Net loss	$ (2,124,541)	$ (1,718,098)	$ (1,892,394)	$ (3,610,492)	$ (5,735,033)	$ (7,446,254)	$ (2,677,171)
Basic net loss per common share (in Dollars per share)	$ (0.18)	$ (0.15)	$ (0.16)	$ (0.31)	$ (0.49)	$ (0.62)	$ (0.26)
Diluted net loss per common share (in Dollars per share)	$ (0.18)	$ (0.15)	$ (0.16)	$ (0.31)	$ (0.49)	$ (0.62)	$ (0.26)
Comprehensive loss	$ (2,129,978)	$ (1,719,628)	$ (1,894,115)	$ (3,613,742)	$ (5,743,720)	$ (7,454,369)	$ (2,680,481)
Cash flows from operating activities:
Net loss	(2,124,541)	(1,718,098)	(1,892,394)	(3,610,492)	(5,735,033)	(7,446,254)	(2,677,171)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock option expense			246,787	500,140	1,022,320	1,354,609	538,587
Net cash used in operating activities			(1,597,146)	(2,880,218)	(4,244,064)	(5,251,748)	(4,297,498)
Cash and cash equivalents at end of year	$ 5,272,565	$ 5,683,787	$ 6,964,314	$ 5,683,787	$ 5,272,565	$ 4,199,311	$ 8,641,027