Balance Sheets - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 43,595,829	$ 30,182,115
Compensating cash arrangement	250,295
Accounts receivable, net of allowance of $265,233 and $380,212 at 2020 and 2019, respectively	5,409,722	5,329,577
Inventories, net	2,846,051	1,847,530
Prepaid expenses and other current assets	1,774,792	1,470,922
Total current assets	53,876,689	38,830,144
Property and equipment, net	234,858	250,443
Operating lease right-of-use assets	2,764,022	4,286,064
Other assets	256,669	218,103
Total assets	57,132,238	43,584,754
Current liabilities:
Short-term debt	457,244
Accounts payable	1,568,581	2,099,097
Accrued liabilities	2,956,130	2,721,104
Deferred revenue	6,189,796	5,092,455
Current portion of operating lease liabilities	2,275,436	2,248,189
Total current liabilities	13,447,187	12,160,845
Long-term debt	1,701,066
Long-term deferred revenue	569,475	554,258
Operating lease liabilities	540,536	2,089,537
Other liabilities	255,517	255,517
Total liabilities	16,513,781	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, 73,678,206 and 68,529,623 shares issued at 2020 and 2019, respectively	73,678	68,530
Additional paid in capital	521,918,228	504,211,040
Treasury stock, 4,015 shares at 2020 and 2019	(205,999)	(205,999)
Accumulated deficit	(486,778,383)	(481,312,774)
Total stockholders’ equity	35,013,134	22,766,407
Total liabilities and stockholders’ equity	$ 57,132,238	$ 43,584,754