Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net loss	$ (26,039,550)	$ (21,397,791)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,473,778	662,562
Accretion of discount on NuvoGen obligation	206,985	281,013
Bad debt expense, net of recoveries		44,854
Provision for excess inventory	723,466	230,754
Amortization of Growth Term Loan discount and issuance costs	551,121	352,415
Loss on settlement of convertible notes		705,217
Amortization of convertible note discount and issuance costs		112,134
Stock-based compensation expense	903,584	405,426
Employee stock purchase plan expense	98,544
Change in redeemable convertible preferred stock warrant liability	0	239,683
Accretion of incentive from landlord	(130,167)
Amortization of premiums and discounts and accrued interest on available-for-sale securities investments	172,045
Loss on disposal of assets	98,685	12,125
Changes in operating assets and liabilities:
Accounts receivable	(661,195)	40,025
Inventory	(33,218)	(746,241)
Prepaid expenses and other	11,889	(334,536)
Accounts payable	10,073	(312,275)
Accrued liabilities	119,928	455,620
Deferred revenue	259,824	6,228
Other long term liabilities		(486)
Net cash used in operating activities	(22,234,208)	(19,243,273)
Investing activities
Purchase of property and equipment	(1,946,515)	(1,338,124)
Sales, redemptions and maturities of available-for-sale securities	29,750,000	7,500,000
Purchase of available-for-sale securities	(3,381,271)	(38,346,765)
Net cash provided by (used in) investing activities	24,422,214	(32,184,889)
Financing activities
Proceeds from initial public offering		47,654,190
Deferred offering costs	(49,630)	(1,002,930)
Proceeds from private investors	2,000,000
Proceeds from Growth Term Loan	5,000,000
Payments on Growth Term Loan	(4,446,396)
Proceeds from convertible notes		4,500,000
Deferred financing costs		(75,523)
Payments on capital leases	(133,079)	(29,242)
Proceeds from exercise of stock options	23,851	34,881
Proceeds from exercise of Series E warrants		8,948
Proceeds from issuance of convertible note warrants		1,354
Proceeds from stock purchased under stock purchase plans		20,000
Proceeds from stock purchased under the employee stock purchase plan	174,674
Payments on NuvoGen obligation	(543,750)
Settlement of fractional common shares		(2,925)
Net cash provided by financing activities	2,025,670	51,108,753
Increase (decrease) in cash and cash equivalents	4,213,676	(319,409)
Cash and cash equivalents at beginning of period	3,293,983	3,613,392
Cash and cash equivalents at end of period	7,507,659	3,293,983
Noncash investing and financing activities
Accretion of preferred stock issuance costs	0	35,046
Accretion of dividends		1,165,932
Deferred offering costs reclassified to distributions in excess of capital		2,297,079
Allocation of Series E warrant convertible notes debt discount		741,828
Conversion of convertible notes and related accrued interest to common stock		4,544,384
Reclassification of convertible preferred stock liability warrants to equity warrants		(1,616,140)
Fixed asset purchases payable and accrued at period end	26,785	122,176
Stock issued for settlement of accrued bonus	(364,910)
Purchase of property and equipment under capital lease	227,147
Incentive from landlord	710,000
Supplemental cash flow information
Cash paid for interest	$ 1,109,359	935,004
Common Stock
Noncash investing and financing activities
Conversion of convertible preferred stock to common stock		(57,356,049)
Series D And E Redeemable Convertible Preferred Stock
Noncash investing and financing activities
Accretion of dividends		1,165,932
Series D and Series E Warrants
Noncash investing and financing activities
Exercise of warrants		(95,914)
Series E Warrants
Noncash investing and financing activities
Accretion of warrant discount		$ 127,616