Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Total Stock-Based Compensation

Total stock-based compensation was as follows:

	Three Months March 31,
	2019		2018
	(in thousands)
Cost of product revenue	$	27	$	15
Research and development		72		49
Sales and marketing		108		43
General and administrative		205		166
Total stock-based compensation	$	412	$	273

Schedule of Estimates Grant-Date Fair Value of Option Awards Using Black-Scholes Option Pricing Model with Assumptions

The Company estimates the grant-date fair value of the Company’s option awards using the Black-Scholes option pricing model. The assumptions for the Black-Scholes model for the three months ended March 31, 2019 and 2018 were as follows:

	Three Months Ended March 31,
	2019	2018
Expected term (in years)	6.08	6.08
Expected volatility	42.4%-42.9%	45.9%
Risk-free interest rate	2.5%-2.6%	1.9%
Expected dividend yield	0%	0%

Schedule of Activity under 2009 Plan and 2019 Plan

Activity under the 2009 Plan and 2019 Plan is set forth below:

	Shares Available for Grant			Number of Shares			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Term		Aggregate Intrinsic Value
									(in years)		(in thousands)
Balance, December 31, 2018		392,299			3,636,358		$	3.54		7.79	$	11,267
Awards authorized		2,000,430			—
2009 Plan shares expired		(293,953	)		—
Options granted		(425,983	)		425,983			14.08
Options exercised		—			(80,515	)		2.12
Options cancelled		21,321			(21,321	)		3.12
Balance, March 31, 2019		1,694,114			3,960,505		$	4.67	7.87		$	114,058
Vested and exercisable, March 31, 2019					1,716,874		$	2.78	6.59		$	52,691
Vested and expected to vest, March 31, 2019					3,960,505		$	4.67	7.87		$	114,058