Share-based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

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

Summary of stock option activity

The following is a summary of service vesting based related stock option activity for the three month period ended March 31, 2017, and the status of stock options outstanding at March 31, 2017:

	Three Month Period Ended
	March 31, 2017
			Wtd. Avg.
			Exercise
	Options		Price
Outstanding at beginning of year		2,513,861	$	1.78
Granted		110,000	$	1.79
Exercised		(107,142)	$	1.12
Forfeited		(47,783)	$	3.59
Expired		(81,352)	$	1.27
Outstanding at March 31, 2017		2,387,584	$	1.79
Stock options exercisable at March 31, 2017		1,257,183	$	1.69

Weighted average assumptions of share based payment

The fair value of share-based payments made with stock options to employees and non-employee directors was estimated on the measurement date using the Black-Scholes model using the following weighted average assumptions.

	Three Month Period Ended
	March 31,
	2017			2016
Risk free interest rate		2.07	%		1.65	%
Dividend yield		0.0	%		0.0	%
Expected term (in years)		5.18			7.00
Volatility		75	%		75	%

Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

The following is a summary of restricted stock activity for the three month period ended March 31, 2017, and the status of unvested restricted stock outstanding at March 31, 2017:

	Three Month Period Ended
	March 31, 2017
	Number of
	Restricted		Grant-Date
	Shares		Fair Value
Unvested outstanding at beginning of year		98,439	$	1.90
Granted		207,350	$	1.76
Vested		(23,439)	$	1.90
Outstanding at March 31, 2017		282,350	$	1.80

Stock compensation expense

We recorded total stock compensation expense for the three month periods ended March 31, 2017 and 2016, as follows:

	Three Month Period Ended
	March 31,
	2017		2016
Research and development costs	$	59,265	$	37,469
Sales and marketing costs		59,619		63,499
General and administrative costs		168,198		77,510
Cost of product sales		42,813		(31,951)
Total	$	329,895	$	146,527