Consolidated Balance Sheets - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 1,918,570	$ 6,309,269
Restricted cash	296,314	176,193
Accounts receivable	1,681,289	823,793
Inventories, net	4,783,887	2,341,360
Prepaid expenses and other current assets	377,762	233,566
Total current assets	9,057,822	9,884,181
Property and equipment, at cost:
Land	896,388	896,388
Building	4,516,301	4,516,301
Machinery and equipment	7,479,790	7,136,578
Property, plant and equipment, gross	12,892,479	12,549,267
Less accumulated depreciation	(8,282,269)	(7,936,056)
Net property and equipment	4,610,210	4,613,211
Patent costs, net of accumulated amortization of $972,553 and $953,491, respectively	260,021	222,461
Trademark costs, net of accumulated amortization of $89,877 and $85,381, respectively	85,964	90,460
Restricted cash		323,863
Total assets	14,014,017	15,134,176
Current liabilities:
Accounts payable	2,995,632	948,875
Unearned revenue	736,819	153,944
Other current liabilities	1,394,150	819,839
Deferred contract liability	110,727	199,160
Current debt, net of deferred financing costs of $7,772 and $0, respectively	4,656,757
Total current liabilities	9,894,085	2,121,818
Long-term debt, net of deferred financing costs of $0 and $45,079		3,119,450
Other long-term liabilities	106,159	121,667
Total long-term liabilities	106,159	3,241,117
Total liabilities	10,000,244	5,362,935
Commitments and contingencies (Note 9)
Stockholders’ equity:
Common stock, $0.01 par value, 175,000,000 shares authorized; 54,267,440 and 54,108,510 shares issued and outstanding, respectively	542,674	541,085
Additional paid-in capital	134,645,911	133,901,406
Accumulated deficit	(131,174,812)	(124,671,250)
Total stockholders’ equity	4,013,773	9,771,241
Total liabilities and stockholders’ equity	$ 14,014,017	$ 15,134,176