Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement, Noncash Expense [Abstract]

Schedule of stock-based compensation expense

The amount of stock-based compensation expense recognized for the years ending December 31, 2019 and 2018 was as follows:

	Year Ended December 31,
	2019		2018
Research and development	$	464,382	$	101,000
General and administrative	1,549,844		2,135,710
Sales and marketing	190,851		57,271
Total stock-based compensation, continuing operations	2,205,077		2,293,981
Total stock-based compensation, discontinued operations	257,719		137,082
Total stock-based compensation	$	2,462,796	$	2,431,063

Summary of option activity

A summary of option activity with service-based vesting conditions for the year ended December 31, 2019 is as follows:

	Options Outstanding
	Number of shares		Weighted average exercise price		Grant date fair value of options		Weighted average remaining contractual term (in years)
Balance at December 31, 2018	3,746,597		$	4.16			7.8
Granted	2,631,927		$	5.70	$	8,106,310
Exercised	(323,403	)	$	2.59
Forfeited	(1,445,554	)	$	5.22	$	4,218,136
Expired	(428,961	)	$	4.99	$	1,062,853
Balance at December 31, 2019	4,180,606		$	4.80			7.9
Exercisable at December 31, 2019	2,228,748		$	4.58			6.8

A summary of option activity with market-based vesting conditions for the year ended December 31, 2019 is as follows:

	Options Outstanding
	Number of shares		Weighted average exercise price per share		Weighted average remaining contractual term (in years)	Aggregate intrinsic value (1)
Balance at December 31, 2018	500,000		$	4.24	9.2
Granted	300,000		$	4.98
Exercised	—
Forfeited	(500,000	)	$	4.24
Balance at December 31, 2019	300,000		$	4.98	9.4	$	123,000
Exercisable at December 31, 2019	—

(1) The aggregate intrinsic value in the above table represents the total pre-tax amount that a participant would receive if the option had been exercised on the last day of the respective fiscal period. Options with a market value less than its exercise value are not included in the intrinsic value amount.

Schedule of fair value assumptions for options

The following table shows the assumptions used to compute stock-based compensation expense for stock options granted to employees and members of the board of directors under the Black-Scholes valuation model, and the assumptions used to compute stock-based compensation expense for market-based stock option grants under a Monte Carlo simulation:

	Year Ended December 31,
Service-based options	2019			2018
Risk-free interest rate	1.47%	—	2.59%	2.51%	—	3.01%
Expected term of options (in years)	5.0	—	6.25	5.0	—	6.25
Expected stock price volatility	55%			55%	—	65%
Expected annual dividend yield	0%			0%
Market-based options
Risk-free interest rate	2.32%			2.84%
Expected term of options (in years)	10			10
Expected stock price volatility	60%			60%
Expected annual dividend yield	0%			0%

Nonvested Restricted Stock Shares Activity

The following table summarizes the Company's RSU activity for the year ended December 31, 2019:

	RSUs Outstanding
	Number of shares		Weighted average grant date fair value
Unvested RSUs at December 31, 2018	445,000		$	4.27
Granted	295,000		$	4.98
Vested	(172,500	)	$	4.52
Forfeited	(300,000	)	$	4.24
Unvested RSUs at December 31, 2019	267,500