Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating Activities
Net loss	$ (8,535)	$ (3,398)
Adjustments to reconcile net loss to cash flows used in operating activities:
Depreciation and amortization expense	115	436
Stock-based compensation expense, net	1,107	281
Change in fair value of warrant liability	0	(1,466)
Warrant valuation expense	0	67
Changes in operating assets and liabilities:
Accounts receivable	(107)	(336)
Inventory	(727)	(187)
Other current assets	(48)	8
Accounts payable and accrued expenses	(283)	(1,103)
Net cash used in operations	(8,478)	(5,698)
Investing Activities:
Purchases of property and equipment	(121)	(20)
Net cash used in investing activities	(121)	(20)
Financing Activities:
Net proceeds from public stock offering	0	8,002
Net proceeds from exercise of warrants	0	1,768
Net proceeds from the sale of preferred stock and warrants	0	184
Net cash provided by financing activities	0	9,954
Effect of exchange rate changes on cash	(1)	(1)
Net (decrease) increase in cash and cash equivalents	(8,600)	4,235
Cash and cash equivalents - beginning of period	15,595	1,323
Cash and cash equivalents - end of period	6,995	5,558
Supplemental schedule of non-cash activities
Warrants issued as inducement to warrant exercise	0	509
Conversion of temporary equity to permanent equity	0	485
Financing fees incurred for subsequent equity financing included in long-term assets and accounts payable	$ 195	$ 0