Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 10,403,697	$ 7,619,748
Short-term investments available-for-sale, at fair value	21,554,318	25,410,222
Restricted cash	3,270,247	3,270,247
Accounts receivable	1,202,469	3,164,176
Inventory, net of allowance of $39,403 at both March 31, 2020 and December 31, 2019	1,637,898	1,269,667
Prepaid expenses and other	525,647	633,522
Total current assets	38,594,276	41,367,582
Operating lease right-of-use assets	1,039,045	1,209,145
Property and equipment, net	2,169,663	2,240,133
Other non-current assets	123,086	302,409
Total assets	41,926,070	45,119,269
Current liabilities:
Accounts payable	1,666,819	1,662,583
Accrued liabilities	1,195,827	1,870,296
Contract liabilities - current	409,449	426,014
NuvoGen obligation - current	1,093,592	1,152,233
MidCap Term Loan payable - current	280,000
Convertible note - current, net of debt issuance costs	2,991,031	2,987,667
Operating lease liabilities - current	696,301	758,932
Other current liabilities	36,205	41,134
Total current liabilities	8,369,224	8,898,859
NuvoGen obligation - non-current, net of discount	4,265,991	4,498,777
MidCap Term Loan payable - non-current, net of discount and debt issuance costs	6,629,972	6,871,545
Operating lease liabilities - non-current	512,718	636,340
Other non-current liabilities	234,981	244,114
Total liabilities	20,012,886	21,149,635
Commitments and Contingencies (Note 15)
Stockholders’ equity:
Series A convertible preferred stock, $0.001 par value; 51,270 shares authorized as of March 31, 2020 and zero shares authorized as of December 31, 2019; 51,270 shares issued and outstanding as of March 31, 2020 and no shares issued and outstanding as of December 31, 2019	51
Common stock, $0.001 par value; 200,000,000 shares authorized at March 31, 2020 and December 31, 2019, 62,196,117 shares issued and outstanding at March 31, 2020 and 58,090,233 shares issued and outstanding at December 31, 2019	62,196	58,090
Additional paid-in-capital	197,578,248	194,234,151
Accumulated other comprehensive income (loss)	48,230	(4,964)
Accumulated deficit	(175,775,541)	(170,317,643)
Total stockholders’ equity	21,913,184	23,969,634
Total liabilities and stockholders' equity	$ 41,926,070	$ 45,119,269