CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net loss	$ (5,608)	$ (935)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	194	199
Provision for inventory obsolescence	41	(47)
Stock based compensation	1,195	372
Change in fair value of derivative liabilities	0	26
Unrealized gain on short term investments	(164)	0
Provision (benefit) for allowance for doubtful accounts	(238)	(9)
Changes in current assets and liabilities:
Trade receivables	349	(277)
Prepaid expenses	(265)	(26)
Inventories	(342)	(136)
Deposits and other assets	(346)	4
Accounts payable	81	514
Accrued severance and related	(99)	0
Accrued expenses and other liabilities	113	(793)
Net cash used in operating activities	(5,089)	(1,108)
Cash flows from investing activities
Purchases of property and equipment	(117)	(139)
Purchases of marketable securities	(18,884)	0
Proceeds of marketable securities	39,842	0
Net cash provided by (used in) investing activities	20,841	(139)
Cash flows from financing activities
Proceeds from stock options exercised	67	0
Repayment of mortgage note payable	0	(60)
Net cash provided by (used in) financing activities	67	(60)
Net change in cash, cash equivalents and restricted cash	15,819	(1,307)
Cash, cash equivalents and restricted cash, beginning of period	16,596	10,668
Cash, cash equivalents and restricted cash, end of period	32,415	9,361
Cash paid for:
Interest expense	0	34
Non cash investing activities:
Cashless exercise of stock options/warrants	710	0
Capitalization of Lease	$ 178	$ 0