Debt and Notes Payable (Tables)

12 Months Ended

Dec. 31, 2015

Debt and Notes Payable

Schedule of long term debt

Long-term debt consisted of the following (in thousands):

	December 31, 2015			December 31, 2014
Massachusetts Development Finance Agency	$	481		$	760
Oxford Finance, LLC	—			6,250
Silicon Valley Bank	—			3,750
	481			10,760
Less total discount	(3		)	(140		)
	478			10,620
Less current installments	295			272
Long-term debt, excluding current installments	$	183		$	10,348

Schedule of principal payments due

The principal payments due as of December 31, 2015 consisted of the following (in thousands):

	Principal Payment
2016	299
2017	182
Total	$	481

Common stock warrants

Debt and Notes Payable

Schedule of inputs and assumptions to calculate the fair value of the warrants

The Company used the Black-Scholes option pricing model to calculate the fair value of the warrants based on the following inputs and assumptions:

Risk-free interest rate	1.6	%
Expected term (in years)	5
Dividend yield	—	%
Expected volatility	50	%

The fair value of warrants at date of grant was estimated using the Black-Scholes option pricing model, based on the following assumptions:

	Year Ended December 31,
	2014	2013
Risk-free interest rate	0.91%-1.71%	0.36% - 0.57%
Expected term (in years)	2.50-5.00	2.5
Dividend yield	—%	—%
Expected volatility	50.00%-55.00%	55.00%