Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net loss	$ (14,291)	$ (8,749)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	78	57
Stock-based compensation	662	145
Fair value of warrants issued	162	152
Fair value of warrants issued to employees for bonuses		244
Non-cash interest expense	422	151
Changes in assets and liabilities:
Accounts receivable	(1,214)	(233)
Inventory	76	(534)
Prepaid expenses and other current assets	(70)	(861)
Other noncurrent assets	5	10
Accounts payable	1,045	685
Accrued liabilities	931	604
Net cash used in operating activities	(12,194)	(8,329)
Cash flows from investing activities:
Purchase of property and equipment	(224)	(48)
Net cash used in investing activities	(224)	(48)
Cash flows from financing activities:
Proceeds from sale of common stock, net of issuance costs	13,886	11,040
Proceeds from note payable	9,910	2,500
Repayments of note payable	(4,833)
Proceeds from exercise of warrants	92	3
Proceeds from exercise of stock options	14
Net cash provided by financing activities	19,069	13,543
Net increase in cash and cash equivalents	6,651	5,166
Cash and cash equivalents - beginning of period	7,360	895
Cash and cash equivalents - end of period	14,011	6,061
Supplemental disclosure:
Cash paid for interest	636	151
Cash paid for income taxes	1	1
Supplemental disclosure of cash flow information as of end of period:
Issuance of warrant in connection with note payable	350	10
Restricted stock awards granted to employees for 2015 accrued bonuses	246
Net transfer of equipment between inventory and property and equipment	$ 60	$ 20