CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash flows from operating activities
Net loss				$ (15,699)	$ (12,946)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation				1,063	1,035
Amortization of intangible assets		$ 309	$ 313	931	944
Non-cash operating lease cost				388	377
Provision for expected credit losses				3	28
Write-down of inventory				307
Loss on disposal of property and equipment				133	27
Stock-based compensation expense				5,323	3,910
Changes in operating assets and liabilities:
Accounts receivable				(794)	912
Prepaid and other current assets				856	(123)
Inventories				(271)	(8,126)
Accounts payable				(103)	772
Accrued liabilities				(324)	(70)
Other				(43)	1,466
Net cash used in operating activities				(8,230)	(11,794)
Cash flows from investing activities
Purchase of property and equipment				(198)	(261)
Proceeds from sale of property and equipment					40
Net cash used in investing activities				(198)	(221)
Cash flows from financing activities
Contributions from PDL					2,366
Distributions to PDL					(1,862)
Proceeds from note payable due to related party					12,400
Sale of common stock to PDL					16,431
Capital contribution from PDL					20,666
Proceeds from issuance of common stock under employee stock purchase plan				170
Net cash provided by financing activities				170	50,001
Net (decrease) increase in cash, cash equivalents and restricted cash				(8,258)	37,986
Cash, cash equivalents and restricted cash at beginning of the period	[1]			40,599	4,715	$ 4,715
Cash and cash equivalents at end the period		$ 32,341	$ 42,701	32,341	42,701	$ 40,599	[1]
Supplemental cash flow information
Cash paid for interest					478
Cash paid for taxes				19
Supplemental schedule of non-cash investing and financing activities
Transfer from Inventories to Equipment under lease, net				$ 3,285	2,521
Phantom stock liability settled with common stock					783
Modification of phantom stock-based awards					306
Common stock issued to extinguish Series A Preferred Stock					37,246
Common stock issued to extinguish note payable to PDL					$ 32,633

[1] Includes restricted cash of $100 as of December 31, 2019.