Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating Activities:
Net loss	$ (9,157)	$ (8,535)
Adjustments to reconcile net loss to cash flows used in operating activities:
Depreciation and amortization	120	115
Stock-based compensation expense, net	701	1,107
Changes in operating assets and liabilities:
Accounts receivable	(146)	(107)
Inventory	(32)	(727)
Other current assets	(75)	(48)
Other assets and liabilities	(18)	0
Accounts payable and accrued expenses	(267)	(283)
Net cash used in operating activities	(8,874)	(8,478)
Investing activities:
Purchases of property and equipment	(158)	(121)
Net cash used in investing activities	(158)	(121)
Financing activities:
Net proceeds from public stock offering, net	10,959	0
Net cash provided by financing activities	10,959	0
Effect of exchange rate changes on cash	(5)	(1)
Net increase (decrease) in cash and cash equivalents	1,922	(8,600)
Cash and cash equivalents - beginning of period	5,480	15,595
Cash and cash equivalents - end of period	$ 7,402	$ 6,995