Annual report pursuant to Section 13 and 15(d)

BALANCE SHEETS (Parenthetical)

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BALANCE SHEETS (Parenthetical) - USD ($)
Dec. 31, 2019
Dec. 31, 2018
Statement of Financial Position [Abstract]    
Accounts receivable, allowance for doubtful accounts $ 32,645 $ 37,500
Patents, accumulated amortization $ 288,967 $ 239,581
Common stock, par value (in dollars per share) $ 0.01 $ 0.01
Common stock, authorized 75,000,000 75,000,000
Common stock, issued 42,239,788 40,932,911
Common stock, outstanding 39,502,557 38,195,680
Treasury stock 2,737,231 2,737,231