Note 10 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands							1 Months Ended		12 Months Ended
	Sep. 14, 2022	Feb. 09, 2022	Sep. 30, 2021	Sep. 22, 2021	Jul. 21, 2020	Jun. 22, 2020	Feb. 28, 2022	Jul. 21, 2020	Jan. 01, 2023	Jan. 02, 2022	Jan. 03, 2021	May 29, 2018
Common Stock, Shares Authorized (in shares)									200,000	200,000
Preferred Stock, Shares Authorized (in shares)									10,000	10,000
Proceeds from Issuance of Common Stock									$ 4,935	$ 1,342	$ 9,296
Payments of Stock Issuance Costs									$ 17	$ 45	$ 1,147
Warrants Issued in Connection with Underwritten Public Offering [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)									$ 19.32
Warrants Issued in Connection with Underwritten Public Offering [Member] | Maximum [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)									386
Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)									797	198	2,642
Common Stock [Member] | Maximum [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)												400
Private Placement [Member]
Shares Issued, Price Per Share (in dollars per share)				$ 5.43
Payments of Stock Issuance Costs				$ 45
Proceeds from Issuance of Common Stock, Net				$ 1,000
Private Placement [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)				125
Registered Direct Offering [Member]
Proceeds from Issuance of Common Stock	$ 3,200	$ 1,500					$ 1,500
Registered Direct Offering [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)			74
Underwritten Public Offering [Member]
Proceeds from Issuance of Common Stock						$ 8,800
Payments of Stock Issuance Costs						$ 1,100
Underwritten Public Offering [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)						2,500
Shares Issued, Price Per Share (in dollars per share)						$ 3.50
Exercise of Option for Overallotment of Shares by Underwriters [Member]
Proceeds from Issuance of Common Stock								$ 500
Payments of Stock Issuance Costs								52
Exercise of Option for Overallotment of Shares by Underwriters [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)					142	375
Underwritten Public Offering, Including Exercise of Overallotment Options by Underwriters [Member]
Proceeds from Issuance of Common Stock								9,300
Payments of Stock Issuance Costs								1,200
Proceeds from Issuance of Common Stock, Net								$ 8,100
Registered Direct Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)	487	310
Proceeds from Issuance of Common Stock	$ 3,200	$ 1,500
Shares Issued, Price Per Share (in dollars per share)	$ 6.57	$ 4.78