Warrants (Tables)

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Schedule of Key Terms of Placement Warrants

The key terms of the 2017 and 2016 Placement Warrants are as follows:

	Issuance Date	Term	Exercise Price Per Share		Warrants Exercised during the Nine Months Ended September 30, 2019		Warrants Outstanding at September 30, 2019
2017 Placement Warrants	January 2017	7 years	$	3.17		90,642		1,618,890
2016 Placement Warrants	August and September 2016	7 years	$	2.95		593,352		537,263
Total						683,994		2,156,153

Summary of Assumptions using Black- Scholes Option Pricing Model to estimate fair value

The fair value of the 2016 and 2017 Placement Warrants at September 30, 2019 and December 31, 2018, respectively, was estimated using the Black-Scholes option-pricing model and the following weighted-average assumptions:

	2017 Placement Warrants				2016 Placement Warrants
	September 30, 2019		December 31, 2018		September 30, 2019	December 31, 2018
Expected term (in years)		4.3		5.1	3.9		4.7
Expected volatility	67.9%		60.8%		67.3%	60.9%
Risk-free interest rate	1.6%		2.5%		1.6%	2.5%
Expected dividend yield	0%		0%		0	0%