Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenue:
Total revenue	$ 19,150	$ 19,250	$ 39,356	$ 37,878
Cost of sales:
Total cost of sales	6,224	6,522	12,603	12,699
Gross profit	12,926	12,728	26,753	25,179
Operating expenses:
Research and development	18,178	13,535	35,751	26,562
General and administrative	13,024	11,725	24,740	20,692
Sales and marketing	7,271	5,317	13,082	10,923
Total operating expenses	38,473	30,577	73,573	58,177
Loss from operations	(25,547)	(17,849)	(46,820)	(32,998)
Other income (expense):
Interest expense	(227)	(356)	(451)	(710)
Interest income	53	43	87	109
Other income (expense), net	(22)	34	35	53
Loss before income taxes	(25,743)	(18,128)	(47,149)	(33,546)
Provision for income taxes	4	26	24	43
Net loss	$ (25,747)	$ (18,154)	$ (47,173)	$ (33,589)
Net loss attributable to common stockholders per share, basic (in dollars per share)	$ (0.38)	$ (0.27)	$ (0.70)	$ (0.51)
Net loss attributable to common stockholders per share, diluted (in dollars per share)	$ (0.38)	$ (0.27)	$ (0.70)	$ (0.51)
Weighted-average shares used in calculating net loss per share, basic (in shares)	67,985,664	66,790,755	67,842,372	66,029,307
Weighted-average shares used in calculating net loss per share, diluted (in shares)	67,985,664	66,790,755	67,842,372	66,029,307
Product revenue
Revenue:
Total revenue	$ 9,468	$ 13,021	$ 19,242	$ 26,554
Cost of sales:
Total cost of sales	2,614	3,332	5,309	7,035
Service revenue
Revenue:
Total revenue	9,682	6,229	20,114	11,324
Cost of sales:
Total cost of sales	$ 3,610	$ 3,190	$ 7,294	$ 5,664