Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (2,821)	$ (2,164)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	261	300
Redeemable warrants valuation adjustment	(393)
Amortization and abandonment of patent and trademark rights	13	30
Equity-based compensation	52	52
Realized loss on sale of marketable securities	(1)	107
Change in assets and liabilities:
Accounts receivable	(41)
Prepaid expenses and other current assets	(327)	(28)
Accounts payable	103	182
Accrued expenses	161	478
Net cash used in operating activities	(2,993)	(1,043)
Cash flows from investing activities:
Sale of marketable securities	500
Purchase of property, equipment and construction in progress	(3)
Lease deposit refund		2
Additions to patent and trademark rights	(11)	(62)
Net cash provided by (used in) investing activities	486	(60)
Cash flows from financing activities:
Payments on capital leases		(1)
Proceeds from sale of stock, net of issuance costs	875	2
Net cash provided by financing activities	875	1
Net decrease in cash and cash equivalents	(1,632)	(1,102)
Cash and cash equivalents at beginning of period	2,408	2,115
Cash and cash equivalents at end of period	776	1,013
Supplemental disclosures of non-cash investing and financing cash flow information:
Unrealized gain on marketable securities	12	147
Stock issued for accounts payable	67
Fair value of redeemable warrants granted	$ 734