Balance Sheets - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 31,650,559	$ 10,796,072
Accounts receivable, net of allowance of $368,191 and $398,847 in 2019 and 2018, respectively	3,830,395	5,021,111
Inventories, net	1,546,716	1,191,666
Prepaid expenses and other current assets	1,022,322	963,700
Total current assets	38,049,992	17,972,549
Property and equipment, net	270,751	343,693
Operating lease right-of-use assets	4,771,187
Other assets	214,042	198,365
Total assets	43,305,972	18,514,607
Current liabilities:
Accounts payable	1,031,975	1,726,360
Accrued liabilities	2,641,254	2,642,481
Deferred revenue	5,283,783	5,825,536
Current portion of operating lease liabilities	2,235,465
Total current liabilities	11,192,477	10,194,377
Long-term deferred revenue	560,508	407,151
Operating lease liabilities	2,574,469
Other liabilities	260,947	641,461
Total liabilities	14,588,401	11,242,989
Series A - Convertible preferred stock:
Convertible preferred stock, Series A, par value $0.001; 23,780 and 23,900 shares outstanding at 2019 and 2018	5,929,749	5,960,475
Stockholders' equity:
Convertible preferred stock, Series B, par value $0.001; 10,000,000 shares authorized, 5,610,121 and no shares outstanding at 2019 and 2018	5,610
Common stock, par value $0.001; 300,000,000 shares authorized, 66,677,111 and 59,058,297 shares issued at 2019 and 2018, respectively	66,677	59,058
Additional paid in capital	503,149,814	478,179,574
Treasury stock, 4,015 shares at 2019 and 2018	(205,999)	(205,999)
Accumulated deficit	(480,228,280)	(476,721,490)
Total stockholders' equity	22,787,822	1,311,143
Total liabilities and stockholders' equity	$ 43,305,972	$ 18,514,607