Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (16,391)	$ (13,301)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	119	95
Noncash interest expense	318	281
Amortization of intangible assets	152	152
Inventory excess and obsolescence charge	682	767
Stock-based compensation expense	2,106	943
Change in operating assets and liabilities:
Accounts receivable, net	(862)	238
Inventory	(1,275)	(750)
Prepaid expenses and other assets	(154)	823
Accounts payable	570	(2,096)
Accrued expenses and other current liabilities	538	(859)
Foreign currency remeasurement (gain) loss	(17)	45
Net cash used in operating activities	(14,214)	(13,662)
Cash flows from investing activities:
Proceeds from the sale and maturity of short-term investments		9,289
Purchase of property and equipment	(47)	(96)
Net cash (used in) provided by investing activities	(47)	9,193
Cash flows from financing activities:
Proceeds from follow-on offering, net of underwriting discounts, commissions and offering costs		45,120
Payment of initial public offering costs		(522)
Proceeds from exercise of stock options	152	44
Net cash provided by financing activities	152	44,642
Effect of exchange rate on cash and cash equivalents	7	(4)
Net (decrease) increase in cash and cash equivalents	(14,102)	40,169
Cash and cash equivalents, beginning of period	74,394	45,302
Cash and cash equivalents, end of period	60,292	85,471
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	1,435	1,482
Supplemental disclosures of noncash investing and financing activities:
Offering costs in accounts payable and accrued expenses and other current liabilities		398
Property and equipment in accounts payable	55
Issuance of common stock for early exercised stock options		$ 2
Reclassification of liability-classified stock-based compensation awards to equity-classified	$ 82