Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating Activities:
Net loss	$ (18,114)	$ (17,032)
Adjustments to reconcile net loss to cash flows used in operating activities:
Depreciation and amortization	239	232
Stock-based compensation expense	1,512	2,087
Changes in operating assets and liabilities:
Accounts receivable	(13)	(241)
Inventories	(343)	(70)
Other current assets	42	(67)
Other assets and liabilities	18	(14)
Accounts payable and accrued expenses	292	545
Net cash used in operations	(16,367)	(14,560)
Investing activities:
Purchase of property and equipment	(490)	(198)
Net cash used in investing activities	(490)	(198)
Financing activities:
Net proceeds from public stock offerings, net	12,665	4,647
Net cash provided by financing activities	12,665	4,647
Effect of exchange rate changes on cash	(9)	(4)
Net decrease in cash and cash equivalents	(4,201)	(10,115)
Cash and cash equivalents - beginning of year	5,480	15,595
Cash and cash equivalents - end of year	1,279	5,480
Supplemental schedule of non-cash activities
Financing fees incurred for subsequent equity financing included in other assets and accounts payable	111	78
Inventory transferred to property, plant and equipment	204	0
Supplemental cash flow information
Cash paid for income taxes	$ 4	$ 2