Statements of Operations - USD ($)	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net revenues	$ 40,206,000	$ 12,776,000
Cost of goods sold	29,435,000	10,719,000
Gross profit	10,771,000	2,057,000
Research and development expenses	4,498,000	1,605,000
Selling, general and administrative expenses	11,177,000	5,737,000
Restructuring expenses	394,000	294,000
Total operating expenses	16,069,000	7,636,000
Loss from operations	(5,298,000)	(5,579,000)
Other expense, net:
Interest expense	(733,000)	(47,000)
Other, net	(618,000)	(70,000)
Total other expense, net	(1,351,000)	(117,000)
Loss before taxes	(6,649,000)	(5,696,000)
Income tax expense	0	0
Net loss	$ (6,649,000)	$ (5,696,000)
Net loss per common share—basic and diluted (in dollars per share)	$ (0.95)	$ (0.98)
Weighted average common shares outstanding—basic and diluted (in shares)	6,974,301	5,793,801