Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 6,975,080	$ 8,432,600
Short-term investments available-for-sale, at fair value	18,056,673	22,681,049
Accounts receivable	3,349,850	5,012,678
Inventory, net of allowance of $39,403 at both March 31, 2019 and December 31, 2018	1,179,041	1,306,609
Prepaid expenses and other	557,521	568,209
Total current assets	30,118,165	38,001,145
Restricted cash	3,270,247	3,270,247
Deferred offering costs	198,088	59,030
Deferred MidCap revolving loan costs	63,099	67,068
Operating lease right-of-use assets	621,429
Property and equipment, net	2,141,107	2,373,790
Total assets	36,412,135	43,771,280
Current liabilities:
Accounts payable	1,414,478	1,849,921
Accrued liabilities	1,329,686	3,358,465
Contract liabilities - current	246,009	332,711
NuvoGen obligation - current	1,232,884	1,290,234
Operating lease liabilities - current	478,804
Other current liabilities	79,091	186,043
Total current liabilities	4,780,952	7,017,374
NuvoGen obligation - non-current, net of discount	5,292,769	5,702,519
Convertible note, related party - net of debt issuance costs	2,977,577	2,974,213
MidCap Term Loan payable - net of discount and debt issuance costs	6,739,815	6,704,641
Operating lease liabilities - non-current, net of discount	441,338
Other non-current liabilities	148,751	280,471
Total liabilities	20,381,202	22,679,218
Commitments and Contingencies (Note 17)
Stockholders’ equity:
Common stock, $0.001 par value; 200,000,000 shares authorized at March 31, 2019 and December 31, 2018, 28,616,633 shares issued and outstanding at March 31, 2019 and 28,585,449 shares issued and outstanding at December 31, 2018	28,616	28,585
Additional paid-in-capital	172,386,803	172,086,909
Accumulated other comprehensive income (loss)	6,339	(3,453)
Accumulated deficit	(156,390,825)	(151,019,979)
Total stockholders’ equity	16,030,933	21,092,062
Total liabilities and stockholders' equity	$ 36,412,135	$ 43,771,280