CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Net sales	$ 12,752,000	$ 11,782,000	$ 11,165,000
Cost of sales:
Cost of sales of products and services	9,449,000	7,663,000	6,706,000
Inventory write-down	0	4,500,000	0
Total cost of sales	9,449,000	12,163,000	6,706,000
Gross profit (loss)	3,303,000	(381,000)	4,459,000
Costs and expenses:
Research and development	26,915,000	21,943,000	21,255,000
Sales, general and administrative	39,193,000	49,236,000	46,904,000
Total costs and expenses	66,108,000	71,179,000	68,159,000
Loss from operations	(62,805,000)	(71,560,000)	(63,700,000)
Other income (expense):
Interest expense	(2,274,000)	(15,545,000)	(15,550,000)
Interest expense related-party	(1,497,000)	0	0
Gain on extinguishment of debt	3,565,000	9,793,000	0
Foreign currency exchange gain (loss)	117,000	(413,000)	252,000
Interest income	551,000	88,000	855,000
Other expense, net	(227,000)	(20,000)	(60,000)
Total other income (expense), net	235,000	(6,097,000)	(14,503,000)
Net loss before income taxes	(62,570,000)	(77,657,000)	(78,203,000)
Benefit (provision) for income taxes	77,000	(45,000)	(5,000)
Net loss	$ (62,493,000)	$ (77,702,000)	$ (78,208,000)
Basic net loss per share (in dollars per share)	$ (0.76)	$ (1.26)	$ (1.40)
Diluted net loss per share ( in dollars per share)	$ (0.76)	$ (1.26)	$ (1.40)
Weighted average shares outstanding, basic (in shares)	82,161	61,727	56,010
Weighted average shares outstanding, diluted (in shares)	82,161	61,727	56,010
Other comprehensive loss:
Net loss	$ (62,493,000)	$ (77,702,000)	$ (78,208,000)
Net unrealized loss on investments	(14,000)	(34,000)	(2,000)
Foreign currency translation adjustment	(326,000)	(117,000)	151,000
Comprehensive loss	$ (62,833,000)	$ (77,853,000)	$ (78,059,000)