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

3 Months Ended

Mar. 31, 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 March 31,
	2020		2019
Cost of product revenue	$	36	$	17
Cost of service and other revenue		68		60
Research and development		242		168
Selling, general, and administrative		1,763		1,039
Total	$	2,109	$	1,284

Summary of stock option activity

		Weighted-average		Remainingcontractual	Aggregateintrinsicvalue
	Options	exerciseprice		life(in years)	(in thousands)
Outstanding at December 31, 2019	2,507,062	$	14.41	7.58	$	24,870
Granted	428,271	$	27.16
Exercised	(63,074)	$	7.86
Cancelled	(31,734)	$	24.29
Outstanding at March 31, 2020	2,840,525	$	16.37	7.75	$	14,641
Vested and expected to vest at March 31, 2020	2,840,525	$	16.37	7.75	$	14,641
Exercisable at March 31, 2020	1,411,836	$	9.93	6.54	$	12,703

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	210,074	$	27.36
Vested	(45,474)	$	18.92
Cancelled	(12,743)	$	26.89
Unvested RSUs as of March 31, 2020	521,980	$	23.22