Warrants, stock-based compensation, stock options, restricted stock and restricted stock units (Tables)

6 Months Ended

Jun. 30, 2020

Warrants, stock-based compensation, stock options, restricted stock and restricted stock units

Summary of share-based compensation expense for all stock awards

Stock-based compensation expense for all stock awards consists of the following (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Cost of product revenue	$	49	$	27	$	85	$	44
Cost of service and other revenue		80		57		148		117
Research and development		290		180		531		348
Selling, general, and administrative		2,082		1,337		3,846		2,376
Total	$	2,501	$	1,601	$	4,610	$	2,885

Summary of stock option activity

		Weighted-average		Remaining contractual	Aggregate intrinsic value
	Options	exercise price		life (in years)	(in thousands)
Outstanding at December 31, 2019	2,507,062	$	14.41	7.58	$	24,870
Granted	457,211	$	27.09
Exercised	(152,570)	$	7.28
Cancelled	(67,262)	$	25.55
Outstanding at June 30, 2020	2,744,441	$	16.65	7.60	$	30,415
Vested and expected to vest at June 30, 2020	2,744,441	$	16.65	7.60	$	30,415
Exercisable at June 30, 2020	1,479,484	$	11.12	6.58	$	24,264

Summary of restricted stock units activity

		Weighted-average
		grant date
		fair value
	Shares	per share
Unvested RSUs as of December 31, 2019	370,123	$	20.48
Granted	224,792	$	27.33
Vested	(93,816)	$	27.26
Cancelled	(21,103)	$	19.94
Unvested RSUs as of June 30, 2020	479,996	$	23.41