Condensed Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net loss	$ (5,379,947)	$ (5,816,274)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	356,204	296,045
Accretion of discount on NuvoGen obligation	(2,952)	50,124
Provision for excess inventory	11,280	192,427
Amortization of Growth Term Loan discount and issuance costs	62,951	122,583
Loss on extinguishment of Growth Term Loan	105,064
Amortization of QNAH Convertible Note issuance costs	3,363
Amortization of MidCap Credit Facility discount and issuance costs	2,924
Stock-based compensation expense	1,143,458	396,646
Employee stock purchase plan expense	14,453	14,888
Accretion of incentive from landlord	(35,500)	(35,500)
Accrued interest on available-for-sale securities investments	(66,195)	(5,573)
Changes in operating assets and liabilities:
Accounts receivable	3,351,907	181,312
Inventory	127,224	63,198
Prepaid expenses and other	(21,494)	64,765
Deferred offering costs	2,953	10,830
Accounts payable	(78,239)	311,036
Accrued liabilities	(2,065,603)	(388,339)
Contract liabilities	(233,078)	(93,874)
Net cash used in operating activities	(2,701,227)	(4,635,706)
Investing activities
Purchase of property and equipment	(457,828)	(65,385)
Sales, redemptions and maturities of available-for-sale securities		1,700,000
Purchase of available-for-sale securities	(25,070,165)
Net cash (used in) provided by investing activities	(25,527,993)	1,634,615
Financing activities
Proceeds from MidCap Credit Facility	7,000,000
MidCap Credit Facility lender fees	(228,459)
Payments on Growth Term Loan	(1,684,626)	(1,546,612)
Payments for extinguishment of Growth Term Loan	(4,276,988)
Proceeds from public offering, net	37,932,290
Public offering costs	(207,974)
Proceeds from ATM Offering, net	556,706
Payments on NuvoGen obligation	(185,574)	(200,000)
Payments on capital leases	(20,786)	(27,199)
Proceeds from exercise of stock options	40,504	35,023
Taxes paid for net share settlement of restricted stock awards	(133,513)
Net cash provided by (used in) financing activities	38,791,580	(1,738,788)
Increase (decrease) in cash and cash equivalents	10,562,360	(4,739,879)
Cash and cash equivalents at beginning of period	9,968,600	7,507,659
Cash and cash equivalents at end of period	20,530,960	2,767,780
Noncash investing and financing activities
Fixed asset purchases payable and accrued at period end	3,486	44,256
Deferred offering costs payable and accrued at period end		76,262
Equipment purchased through capital lease	31,340
Debt issuance costs payable and accrued at period end	193,931
MidCap Term Loan fees and warrant discount	389,000
Retirement of treasury stock		75,000
Supplemental cash flow information
Cash paid for interest	$ 83,397	225,713
Cash paid for taxes		$ 280