Stockholders' Equity, Equity Incentive Plans and Warrants (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-based compensation expense

The following table summarizes share-based compensation expense, (in thousands):

	Year Ended December 31,
	2012		2013		2014
Cost of goods sold	$	617	$	334	$	350
Sales and marketing	419		274		353
Research and development	1,705		1,054		1,304
General and administrative	1,024		1,028		1,138
Share-based compensation expense before taxes	3,765		2,690		3,145
Related deferred income tax benefits	—		—		—
Share-based compensation expense	$	3,765	$	2,690	$	3,145
Share-based compensation expense is derived from:
Stock options	$	1,508	$	1,924	$	2,642
Restricted stock awards	1,958		489		181
2014 and 2000 ESPP	299		277		322
Total	$	3,765	$	2,690	$	3,145

Summary of stock option activity

A summary of stock option activity for 2014 is as follows:

	Number of shares		Weighted average exercise price		Weighted average remaining contractual term (in years)	Aggregate intrinsic value
Outstanding at January 1, 2014	9,850,498		$	2.58
Granted	2,370,500		4.04
Exercised	(1,184,829	)	2.20
Forfeited	(554,079	)	2.53
Expired	(529,146	)	8.89
Outstanding at December 31, 2014	9,952,944		$	2.64	4.34	$	18,369,137
Vested and expected to vest at December 31, 2014	9,578,949		$	2.61	4.27	$	17,994,450
Exercisable at December 31, 2014	6,141,839		$	2.48	3.52	$	12,604,603

Summary of restricted stock activity

A summary of restricted stock award activity for 2014 is as follows:

	Number of shares		Weighted average grant date fair value
Outstanding at January 1, 2014	92,811		$	1.73
Granted	80,000		4.32
Vested	(116,661	)	2.25
Forfeited	(250	)	2.90
Outstanding and unvested at December 31, 2014	55,900		$	4.33

Schedule of valuation assumptions for equity awards

To estimate compensation expense for the years ended December 31, 2012, 2013, and 2014 we used the Black-Scholes pricing model with the following weighted-average assumptions for equity awards granted:

	EIP and NEDSOP						ESPP
	Year Ended December 31,						Year Ended December 31,
	2012		2013		2014		2012		2013		2014
Risk-free interest rate	1.19	%	1.07	%	1.59	%	0.12	%	0.09	%	0.05	%
Expected dividend yield	—	%	—	%	—	%	—	%	—	%	—	%
Volatility	81	%	82	%	70	%	64	%	63	%	60	%
Expected Term	5.2 years		5.3 years		4.9 years		0.5 years		0.5 years		0.5 years
Forfeiture Rate	0%-10.62%		0%-9.45%		0%-10.05%		—	%	—	%	—	%