Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (21,397,791)	$ (13,958,408)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	662,562	496,595
Accretion of discount on NuvoGen obligation	281,013	187,017
Bad debt expense, net of recoveries	44,854	115,068
Provision for excess inventory	230,754	54,269
Amortization of deferred financing costs	44,666	13,841
Amortization of discount on term loan	170,954	84,676
Amortization of final payment premium on term loan	158,707	56,201
Loss on settlement of convertible notes	705,217
Amortization of discount on convertible notes	90,222
Stock-based compensation expense	405,426	184,966
Change in redeemable convertible preferred stock warrant liability	239,683	388,936
Loss on disposal of assets	12,125	35,960
Changes in operating assets and liabilities:
Accounts receivable	40,025	(312,340)
Inventory	(746,241)	(746,982)
Prepaid expenses and other	(334,536)	52,092
Accounts payable	(312,275)	198,193
Accrued liabilities	455,620	278,291
Deferred revenue	6,228	(95,442)
Other long term liabilities	(486)	(29,549)
Net cash used in operating activities	(19,243,273)	(12,996,616)
Investing activities
Purchase of property and equipment	(1,338,124)	(857,677)
Sales, redemptions and maturities of available-for-sale securities	7,500,000
Purchase of available-for-sale securities	(38,346,765)
Net cash used in investing activities	(32,184,889)	(857,677)
Financing activities
Proceeds from exercise of stock options	34,881	21,482
Proceeds from stock issued under stock purchase plan	20,000
Draws on line of credit		750,000
Payments on line of credit		(750,000)
Payments on NuvoGen obligation	0	(1,206,250)
Deferred offering costs	(1,002,930)	(1,205,122)
Deferred financing costs	(75,523)
Payments on equipment lease	(29,242)	(21,932)
Proceeds from term loan		10,680,000
Proceeds from issuance of convertible note warrants	1,354
Settlement of fractional common shares	(2,925)
Proceeds from convertible notes	4,500,000
Proceeds from initial public offering	47,654,190
Net cash provided by financing activities	51,108,753	15,652,396
(Decrease) increase in cash and cash equivalents	(319,409)	1,798,103
Cash and cash equivalents at beginning of year	3,613,392	1,815,289
Cash and cash equivalents at end of year	3,293,983	3,613,392
Noncash investing and financing activities
Accretion of preferred stock issuance costs	35,046	102,677
Accretion of Series E warrant discount	(127,616)	(313,152)
Adjustment to Series B book value		(112,903)
Accretion of Series D and E redeemable convertible preferred stock dividends	1,165,932	3,244,572
Deferred offering costs reclassified to distributions in excess of capital	2,297,079
Accrual of deferred offering and finance costs		178,000
Allocation of Series E warrant convertible notes debt discount	741,828
Allocation of Series E warrant debt discount		301,507
Conversion of convertible notes and related accrued interest to common stock	4,544,384
Fixed asset purchases payable at period end	122,176
Reclassification of convertible preferred stock liability warrants to equity warrants	(1,616,140)
Supplemental cash flow information
Cash paid for interest	935,004	368,331
Common Stock
Noncash investing and financing activities
Conversion of convertible preferred stock to common stock	(57,356,049)	(5,881,442)
Series D and Series E Warrants
Financing activities
Proceeds from exercise of Series D and E warrants	8,948	251
Noncash investing and financing activities
Net exercise of Series D and Series E warrants	(95,914)	(4,020)
Series E Warrants
Noncash investing and financing activities
Net exercise of Series D and Series E warrants	0	0
Accretion of Series E warrant discount	127,616	313,152
Series E Redeemable Convertible Preferred Stock
Financing activities
Proceeds from sale of Series E preferred stock, net of issuance costs		7,383,967
Noncash investing and financing activities
Net exercise of Series D and Series E warrants	(11,312)
Accretion of Series E warrant discount	$ 127,616	313,152
Series E Redeemable Convertible Preferred Stock | Series E Warrants
Noncash investing and financing activities
Net exercise of Series D and Series E warrants		$ (1,889,201)