Stock Incentive Plans (Tables)

6 Months Ended

Jun. 30, 2017

Stock Incentive Plans

Summary of incentive plan activity

						Weighted		Weighted Average
	Shares					Average		Remaining	Aggregate
	Available		Stock Options		RSUs	Stock Option		Contractual Life	Intrinsic
	for Grant		Outstanding		Outstanding	Exercise Price		(Years)	Value
Combined Incentive Plan Balance—December 31, 2016	39,988		2,571,220		20,789	$	2.52	8.77	$	—
2013 Equity Incentive Plan Activity:
None
2014 Stock Incentive Plan Activity:
Additional shares authorized	280,142
Q1 Options granted	(18,000	)	18,000			0.71
Q1 Options cancelled	60,570		(60,570	)		1.67
Q2 Options granted	(20,000	)	20,000			0.79
Q2 Options cancelled	107,799		(107,799	)		1.47
Combined Incentive Plan Balance—June 30, 2017	450,499		2,440,851		20,789	$	2.56	8.44	$	—
Options vested and exercisable—June 30, 2017			1,297,589			$	3.21	7.93	$	—
Options vested and expected to vest—June 30, 2017			2,128,319			$	2.60	8.38	$	—

Summary of stock-based compensation expense

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2017		2016		2017		2016
Research and development expense	$	58,173	$	37,284	$	123,972	$	62,617
Sales and marketing expense	7,711		—		15,369		8,681
General and administrative expense	150,250		88,238		304,829		157,766
Total	$	216,134	$	125,522	$	444,170	$	229,064

Employee stock options

Stock Incentive Plans

Schedule of estimated grant-date fair value of stock options calculated using the Black-Scholes option-pricing model

	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2017	2016	2017	2016
Weighted-average volatility	76.75%	66.25-69.14%	74.26-76.75%	66.25-69.14%
Weighted-average expected term (years)	5.82	5.67-5.82	5.82	5.67-5.82
Risk-free interest rate	1.97%	1.36-1.49%	1.97-1.98%	1.36-1.49%
Expected dividend yield	—	—	—	—

Non-employee stock options

Stock Incentive Plans

Schedule of estimated grant-date fair value of stock options calculated using the Black-Scholes option-pricing model

	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2017	2016	2017	2016
Weighted-average volatility	—	78.30-80.04%	—	78.30-80.04%
Weighted-average expected term (years)	—	9.19-9.25	—	9.19-9.44
Risk-free interest rate	—	1.44-1.66%	—	1.44-1.74%
Expected dividend yield	—	—	—	—