Antidilutive securities excluded from computation of diluted net loss per share (Details) - shares	3 Months Ended	12 Months Ended
Jul. 31, 2022	Apr. 30, 2022
Accounting Policies [Abstract]
Series B Preferred Stock, as converted	822,230	822,230
Stock options	3,634,142	3,694,142
Warrants	1,539,999	1,539,999
Restricted stock	971,701	1,083,675
Total	6,968,072	7,140,046

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=124432515&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration