Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (5,128)	$ (5,014)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	444	504
Redeemable warrants valuation adjustment	(131)	(923)
Amortization of patent and trademark rights	30	17
Equity-based compensation	612	101
Realized gain (loss) on sale of marketable securities		(6)
Gain on sale of building	(223)
Amortization of finance costs and debt settlement expenses	168
Change in assets and liabilities:
Accounts receivable	(11)	(98)
Prepaid expenses and other current assets	(398)	(298)
Accounts payable	126	85
Accrued expenses	(734)	331
Net cash used in operating activities	(5,245)	(5,301)
Cash flows from investing activities:
Sale of marketable securities		1,500
Purchase of property, equipment and construction in progress		(3)
Proceeds from sale of building	1,050
Purchase of patent and trademark rights	(57)	(14)
Net cash provided by investing activities	993	1,483
Cash flows from financing activities:
Proceeds from lease financing obligation	4,080
Settlement costs of lease financing obligation	(268)
Payment of financing obligation payment	(97)
Debt issuance costs		(89)
Proceeds from note payable		606
Payoff of mortgage note payable	(1,957)
Security deposits paid	(114)
Proceeds from sale of stock, net of issuance costs	4,764	2,115
Net cash provided by financing activities	6,408	2,632
Net increase (decrease) in cash and cash equivalents	2,156	(1,186)
Cash and cash equivalents at beginning of period	1,412	2,408
Cash and cash equivalents at end of period	3,568	1,222
Supplemental disclosures of non-cash investing and financing cash flow information:
Unrealized gain (loss) on marketable securities	(20)	29
Stock issued to settle accounts payable	$ 280	$ 106