Quarterly report pursuant to Section 13 or 15(d)

Common Stock, Preferred Stock and Warrants - Assumptions used to estimate fair value of warrants (Details)

v3.21.1
Common Stock, Preferred Stock and Warrants - Assumptions used to estimate fair value of warrants (Details) - Warrants
9 Months Ended
Jan. 31, 2021
Expected volatility, minimum 86.00%
Expected volatility, maximum 104.00%
Expected dividends 0.00%
Expected term, minimum 4 years 8 months 1 day
Expected term, maximum 5 years
Risk-free interest rate, minimum 0.10%
Risk-free interest rate, maximum 0.41%