Nature of business, basis of presentation and summary of significant accounting policies (Details Textual) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 945	$ 486	$ 307
Accumulated deficit	(119,184)	(114,420)
Amortization of debt discount and deferred financing costs	44	64
Depreciation expense	15	12
Patent amortization expense	365	365
Impairment of Long-Lived Assets Held-for-use	0	0
Marketing expense	$ 15	$ 15
Estimated remaining weighted average useful lives of patents	P4Y
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Estimated useful life of related assets, for patents amortization	5 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Estimated useful life of related assets, for patents amortization	17 years