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7. Stock-Based Compensation (Details 1) - $ / shares
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Share-based Payment Arrangement, Noncash Expense [Abstract]    
Dividend-yield 0.00% 0.00%
Risk-free interest rate 0.70% 1.08%
Expected volatility 97.45% 87.43%
Expected life (years) 6 years 6 months 4 days 6 years 11 months 5 days
Market value per share on grant date $ 3.09 $ 0.71
Weighted average fair value per share of common stock $ 2.44 $ 0.54