Investigation of Temperature Performance of Silica Gel Covered Flexible Array Optical Fiber Temperature Probe

This paper presents the design, fabrication and reliability testing of a novel flexible array of sensors based on fiber Bragg grating (FBG) for surface temperature sensing applications. The structure of the proposed optical fiber temperature probe (OFTP) consists of a rectangular metal base over which a room temperature cured silica gel is laid out. The FBGs pass through hollow capillary channels located in the middle of the silica gel layer. The use of the silica gel allows obtaining a tiny deformable surface that provides the capability to adapt its contact surface to better match the measured object. Based on a specific design, a silica gel of 80 mm × 80 mm × 5 mm with eight parallel arranged capillary channels is fabricated on a 15 mm-thick rectangular metal protruding platform. Two FBGs are placed into capillary channels in symmetrical positions close to a central hole, respectively. One is placed inside a Teflon capillary tube, along with a thermocouple used as a reference, while the other FBG goes directly through the capillary channel. The prototype is tightly attached to a heating plate to obtain a uniform temperature loading. The experimental results show that the designed flexible array temperature probe offers reliable and precise temperature measurements when compared to the real value at the panel. Although FBGs have been used in this proof-of-concept demonstration, distributed fiber sensing methods can also be used to obtain a distributed temperature profile.