Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating activities:
Net loss	$ (12,838,000)	$ (18,838,000)
Adjustments required to reconcile net income to net cash used in operating activities:
Change in fair value of derivative and warrant liabilities	(2,010,000)	(4,538,000)
Impairment charges	5,800,000	9,547,000
Stock-based compensation	700,000	1,995,000
Deferred taxes	(1,302,000)	(556,000)
Charge for common stock issuance	519,000
Costs related to equity offerings		569,000
Warrants and other non-cash adjustments, net	22,000	193,000
Depreciation expenses	343,000	338,000
Amortization of patents	31,000	31,000
Changes in operating assets and liabilities net of acquisitions:
Accounts payable and accrued liabilities	(838,000)	406,000
Prepaid expenses, accounts receivable and other current assets	381,000	247,000
Net cash used in operating activities	(9,192,000)	(10,606,000)
Investing activities:
Purchases of property and equipment	(58,000)	(279,000)
Net cash used in investing activities	(58,000)	(279,000)
Financing activities:
Costs of Series B redeemable convertible preferred stock conversion to common stock		(173,000)
Dividend payments		(80,000)
Proceeds from sale of common stock and related warrants, net of offering costs	9,353,000	7,566,000
Proceeds from exercises of warrants	130,000
Proceeds from stock issuance under employee stock purchase plan	3,000	13,000
Principal payments on note payable	(815,000)	(100,000)
Net cash provided by financing activities	8,671,000	7,226,000
Net (decrease) increase in cash and cash equivalents	(579,000)	(3,659,000)
Cash and cash equivalents, beginning of period	5,711,000	9,370,000
Cash and cash equivalents, end of period	5,132,000	5,711,000
Supplemental schedule of non-cash financing activities:
Accretion of Series B redeemable convertible preferred stock		1,858,000
Fair value of warrant liability upon issuance		4,745,000
Offering costs included in accounts payable		$ 69,000
Property and equipment included in accounts payable	$ 39,000