Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	IPO	IPO Common Stock	IPO Additional Paid-in Capital [Member]
Beginning balance, shares at Jan. 02, 2018		43,550,329	2,423,871
Beginning balance at Jan. 02, 2018	$ 35,861	$ 436	$ (35,000)	$ 171,613	$ (101,188)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from exercise of stock options, warrants and employee stock purchase plan (in shares)		289,684					2,500,000
Proceeds from exercise of stock options, warrants and employee stock purchase plan	654	$ 2		652		$ 23,157	$ 25	$ 23,132
Stock-based compensation expense	2,269			2,269
Net loss	(8,460)				(8,460)
Ending balance at Oct. 02, 2018	51,975	$ 463	$ (35,000)	197,666	(111,154)
Ending balance, shares at Oct. 02, 2018		46,340,013	2,423,871
Beginning balance, shares at Jul. 03, 2018		43,690,395	2,423,871
Beginning balance at Jul. 03, 2018	26,169	$ 437	$ (35,000)	172,936	(112,204)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from exercise of stock options, warrants and employee stock purchase plan (in shares)		149,618					2,500,000
Proceeds from exercise of stock options, warrants and employee stock purchase plan	947	$ 1		946		$ 23,157	$ 25	$ 23,132
Stock-based compensation expense				652
Net loss	1,050				1,050
Ending balance at Oct. 02, 2018	51,975	$ 463	$ (35,000)	197,666	(111,154)
Ending balance, shares at Oct. 02, 2018		46,340,013	2,423,871
Beginning balance, shares at Jan. 01, 2019		46,353,309	2,423,871
Beginning balance at Jan. 01, 2019	52,681	$ 464	$ (35,000)	198,352	(111,135)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from exercise of stock options, warrants and employee stock purchase plan (in shares)		192,683
Proceeds from exercise of stock options, warrants and employee stock purchase plan	(284)	$ 1		(285)
Stock-based compensation expense	1,811			1,811
Net loss	2,830				2,830
Ending balance at Oct. 01, 2019	51,046	$ 465	$ (35,000)	199,878	(114,297)
Ending balance, shares at Oct. 01, 2019		46,545,992	2,423,871
Beginning balance, shares at Jul. 02, 2019		46,508,586	2,423,871
Beginning balance at Jul. 02, 2019	46,903	$ 465	$ (35,000)	199,978	(118,540)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from exercise of stock options, warrants and employee stock purchase plan (in shares)		37,406
Proceeds from exercise of stock options, warrants and employee stock purchase plan	(49)	$ 0		(49)
Stock-based compensation expense	(51)			(51)
Net loss	4,243				4,243
Ending balance at Oct. 01, 2019	$ 51,046	$ 465	$ (35,000)	$ 199,878	$ (114,297)
Ending balance, shares at Oct. 01, 2019		46,545,992	2,423,871