Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Measurements

Schedule of financial assets and liabilities at fair value by respective level of the fair value hierarchy

	Level 1		Level 2		Level 3		Total
	(in thousands)
At December 31, 2017
Assets:
Cash and cash equivalents	$	3,250	$	—	$	—	$	3,250
Trade accounts receivable		314		—		—		314
Short-term investments		238		—		—		238
	$	3,802	$	—	$	—	$	3,802
At December 31, 2016
Assets:
Cash and cash equivalents	$	2,588	$	—	$	—	$	2,588
Trade accounts receivable		380		—		—		380
Trade accounts receivable - related party		643		—		—		643
Short-term investments		334		—		—		334
	$	3,945	$	—	$	—	$	3,945
Liabilities:
Warrant liability - related party	$	—	$	—	$	976	$	976
Warrant liability		—		—		922		922
	$	—	$	—	$	1,898	$	1,898

Schedule of significant inputs to the valuation model

	December 31,
	2016
Company's ending stock price	$	0.58
Company's stock volatility		110%
Applicable risk free interest rate		1.39%

Summary of change in fair value of the warrant liability

		Fair Value Measurements
		Using Significant Unobservable
		Inputs (Level 3)
	Warrant Liabilities
	(in thousands)
Ending balance at December 31, 2015	$	1,898
Change in estimated fair value		(364)
Ending balance at December 31, 2016	$	1,534