Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities:
Net loss	$ (4,594)	$ (3,665)
Adjustments to reconcile net loss to net cash used in operating activities:
Write-off of inventory	3
Depreciation	22	23
Reduction in the carrying amount of right-of-use assets	118	105
Share-based compensation	941	690
Changes in operating assets and liabilities:
Accounts receivable	(32)	(13)
Inventory	1	23
Prepaid expenses and other current assets	189	160
Accounts payable	194	122
Accrued liabilities and other current liabilities	293	(36)
Operating lease liability - current	20
Deferred revenue	(2)
Operating lease liability - noncurrent	(146)	126
Net cash used in operating activities	(2,993)	(2,465)
Investing activities:
Purchase of property and equipment	(5)	(55)
Net cash used provided in investing activities	(5)	(55)
Financing activities:
Net cash provided by financing activities
Net change in cash and cash equivalents	(2,998)	(2,520)
Cash and cash equivalents at beginning of period	5,585	5,358
Cash and cash equivalents at end of period	2,587	2,838
Supplementary disclosure of non-cash activities:
Right-of-use assets obtained in exchange for lease obligations		$ 1,505