Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net loss	$ (12,110,000)	$ (12,838,000)
Adjustments required to reconcile net loss to net cash used in operating activities:
Change in fair value of derivative liabilities	(86,000)	(2,010,000)
Stock-based compensation	478,000	700,000
Depreciation	358,000	343,000
Amortization of patents	31,000	31,000
Impairment charges	1,930,000	5,800,000
Deferred taxes	(328,000)	(1,302,000)
Charge for common stock issuance		519,000
Other non-cash adjustments, net		22,000
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	2,000	381,000
Accounts payable and accrued liabilities	343,000	(838,000)
Net cash used in operating activities	(9,382,000)	(9,192,000)
Investing activities:
Purchases of property and equipment	(44,000)	(58,000)
Net cash used in investing activities	(44,000)	(58,000)
Financing activities:
Proceeds from sale of common stock and related warrants, net of offering costs	12,248,000	9,353,000
Proceeds from exercises of warrants	198,000	130,000
Proceeds from stock issuances under employee stock purchase plan	5,000	3,000
Principal payments on note payable		(815,000)
Net cash provided by financing activities	12,451,000	8,671,000
Net increase (decrease) in cash and cash equivalents	3,025,000	(579,000)
Cash and cash equivalents, beginning of period	5,132,000	5,711,000
Cash and cash equivalents, end of period	8,157,000	5,132,000
Supplemental schedule of non-cash financing activities:
Offering costs included in accounts payable	$ 260,000
Property and equipment included in accounts payable		$ 39,000