Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units (Tables)

12 Months Ended

Dec. 31, 2019

Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units

Schedule of common stock reserved

	As of December 31,
	2019	2018
Common stock warrants	10,000	76,041
Common stock options and unvested restricted common stock	2,916,991	2,838,402
Shares reserved for future awards under compensation plan	882,715	2,433,999
	3,809,706	5,348,442

Summary of warrant activity

		Weighted
	Issued and	Average
	exercisable	Exercise Price
As of December 31, 2018	76,041	$	10.10
Issued	—
Exercised	(66,041)		10.90
Cancelled	—
As of December 31, 2019	10,000	$	4.83

Summary of share-based compensation expense for all stock awards

	December 31,
	2019		2018		2017
Cost of product revenue	$	86	$	55	$	24
Cost of service and other revenue		238		173		52
Research and development		718		513		180
Selling, general, and administrative		5,346		4,143		1,912
Total	$	6,388	$	4,884	$	2,168

Summary of stock option activity

		Weighted-average		Remainingcontractual	Aggregateintrinsicvalue
	Options	exerciseprice		life(in years)	(in thousands)
Outstanding at December 31, 2018	2,476,911	$	9.65	7.73	$	22,108
Granted	882,959	$	24.20
Exercised	(414,672)	$	6.80
Cancelled	(438,136)	$	14.37
Outstanding at December 31, 2019	2,507,062	$	14.41	7.58	$	24,870
Vested and expected to vest at December 31, 2019	2,507,062	$	14.41	7.58	$	24,870
Exercisable at December 31, 2019	1,284,900	$	8.70	6.46	$	19,239

Summary of restricted stock units activity

		Weighted-average
		grant date
		fair value
	Shares	per share
Unvested RSUs as of December 31, 2018	321,662	$	15.84
Granted	246,588	$	24.22
Vested	(136,062)	$	17.11
Cancelled	(62,065)	$	18.82
Unvested RSUs as of December 31, 2019	370,123	$	20.48