Balance Sheets - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 42,452,713	$ 43,939,512
Restricted cash - current	1,336,000
Compensating cash arrangement	250,919	250,620
Accounts receivable, net of allowance of $122,570 and $123,614 at 2021 and 2020, respectively	7,290,762	3,515,136
Inventories, net	3,536,300	3,295,457
Prepaid expenses and other current assets	1,674,554	1,716,014
Total current assets	56,541,248	52,716,739
Property and equipment, net	202,504	195,129
Restricted cash	93,331
Operating lease right-of-use assets	1,695,664	2,235,442
Other assets	284,946	308,515
Total assets	58,817,693	55,455,825
Current liabilities:
Short-term debt	1,914,692	1,185,058
Accounts payable	2,270,432	1,608,636
Accrued liabilities	2,578,298	3,209,235
Deferred revenue	8,188,296	5,282,770
Current portion of operating lease liabilities	1,734,699	2,287,487
Total current liabilities	16,686,417	13,573,186
Long-term debt	243,617	973,252
Long-term deferred revenue	1,328,272	548,915
Other liabilities	210,096	131,231
Total liabilities	18,468,402	15,226,584
Series A - Convertible preferred stock:
Convertible preferred stock, Series A, par value $0.001; 22,408 and 22,513 shares outstanding at 2021 and 2020, respectively	5,578,437	5,605,323
Stockholders’ equity:
Convertible preferred stock, Series B, par value $0.001; 10,000,000 shares authorized, 5,610,121 shares outstanding at 2021 and 2020	5,610	5,610
Common stock, par value $0.001; 300,000,000 shares authorized,74,089,659 and 73,694,203 shares issued at 2021 and 2020, respectively	74,090	73,694
Additional paid in capital	524,388,783	522,709,846
Treasury stock, 4,015 shares at 2021 and 2020	(205,999)	(205,999)
Accumulated deficit	(489,491,630)	(487,959,233)
Total stockholders’ equity	34,770,854	34,623,918
Total liabilities and stockholders’ equity	$ 58,817,693	$ 55,455,825