Balance Sheets - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 43,939,512	$ 30,182,115
Compensating cash arrangement	250,620
Accounts receivable, net of allowance of $123,614 and $380,212 at 2020 and 2019, respectively	3,515,136	5,329,577
Inventories, net	3,295,457	1,847,530
Prepaid expenses and other current assets	1,716,014	1,470,922
Total current assets	52,716,739	38,830,144
Property and equipment, net	195,129	250,443
Operating lease right-of-use assets	2,235,442	4,286,064
Other assets	308,515	218,103
Total assets	55,455,825	43,584,754
Current liabilities:
Short-term debt	1,185,058
Accounts payable	1,608,636	2,099,097
Accrued liabilities	3,209,235	2,721,104
Deferred revenue	5,282,770	5,092,455
Current portion of operating lease liabilities	2,287,487	2,248,189
Total current liabilities	13,573,186	12,160,845
Long-term debt	973,252
Long-term deferred revenue	548,915	554,258
Operating lease liabilities		2,089,537
Other liabilities	131,231	255,517
Total liabilities	15,226,584	15,060,157
Series A - Convertible preferred stock:
Convertible preferred stock, Series A, par value $0.001; 22,513 and 23,110 shares outstanding at 2020 and 2019, respectively	5,605,323	5,758,190
Stockholders’ equity:
Convertible preferred stock, Series B, par value $0.001; 10,000,000 shares authorized, 5,610,121 shares outstanding at 2020 and 2019	5,610	5,610
Common stock, par value $0.001; 300,000,000 shares authorized, 73,694,203 and 68,529,623 shares issued at 2020 and 2019, respectively	73,694	68,530
Additional paid in capital	522,709,846	504,211,040
Treasury stock, 4,015 shares at 2020 and 2019	(205,999)	(205,999)
Accumulated deficit	(487,959,233)	(481,312,774)
Total stockholders’ equity	34,623,918	22,766,407
Total liabilities and stockholders’ equity	$ 55,455,825	$ 43,584,754