Balance Sheets - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 42,054,296	$ 43,939,512
Restricted cash - current	1,484,018
Compensating cash arrangement	251,232	250,620
Accounts receivable, net of allowance of $154,727 and $123,614 at 2021 and 2020, respectively	4,651,804	3,515,136
Inventories, net	4,146,691	3,295,457
Prepaid expenses and other current assets	2,646,806	1,716,014
Total current assets	55,234,847	52,716,739
Property and equipment, net	291,578	195,129
Restricted cash	382,813
Operating lease right-of-use assets	1,143,355	2,235,442
Other assets	283,093	308,515
Total assets	57,335,686	55,455,825
Current liabilities:
Short-term debt		1,185,058
Accounts payable	1,124,178	1,608,636
Accrued liabilities	2,857,479	3,209,235
Deferred revenue	8,284,600	5,282,770
Current portion of operating lease liabilities	1,169,378	2,287,487
Total current liabilities	13,435,635	13,573,186
Long-term debt		973,252
Long-term deferred revenue	1,648,792	548,915
Other liabilities	206,596	131,231
Total liabilities	15,291,023	15,226,584
Series A - Convertible preferred stock:
Convertible preferred stock, Series A, par value $0.001; 22,407 and 22,513 shares outstanding at 2021 and 2020, respectively	5,578,181	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, 74,428,865 and 73,694,203 shares issued at 2021 and 2020, respectively	74,429	73,694
Additional paid in capital	527,294,470	522,709,846
Treasury stock, 4,015 shares at 2021 and 2020	(205,999)	(205,999)
Accumulated deficit	(490,702,028)	(487,959,233)
Total stockholders’ equity	36,466,482	34,623,918
Total liabilities and stockholders’ equity	$ 57,335,686	$ 55,455,825