Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net loss	$ (7,790,000)	$ (10,486,000)
Adjustments required to reconcile net loss to net cash used in operating activities:
Change in fair value of derivative liabilities	46,000	(1,997,000)
Stock-based compensation	366,000	568,000
Charge for common stock issuance (Note 6)		519,000
Depreciation	268,000	255,000
Amortization of patents	23,000	23,000
Other non-cash adjustments, net		22,000
Impairment charges		5,800,000
Deferred taxes		(1,302,000)
Changes in operating assets and liabilities:
Accounts payable and accrued expenses	218,000	(595,000)
Prepaid expenses and other current assets	(85,000)	370,000
Net cash used in operating activities	(6,954,000)	(6,823,000)
Investing activities:
Purchases of property and equipment	(41,000)	(40,000)
Net cash used in investing activities	(41,000)	(40,000)
Financing activities:
Proceeds from sale of common stock and related warrants, net of offering costs	6,159,000	9,353,000
Proceeds from exercises of warrants	198,000	31,000
Proceeds from stock issuance under employee stock purchase plan	5,000	3,000
Principal payments on note payable		(510,000)
Net cash provided by financing activities	6,362,000	8,877,000
Net increase (decrease) in cash and cash equivalents	(633,000)	2,014,000
Cash and cash equivalents, beginning of period	5,132,000	5,711,000
Cash and cash equivalents, end of period	4,499,000	$ 7,725,000
Supplemental schedule of non-cash financing activities:
Offering costs included in accounts payable	$ 277,000