High temperature strain sensor based on a fiber Bragg grating and rhombus metal structure

Abstract

In this paper, a novel high temperature strain sensor based on a polyimide-coated fiber Bragg grating (FBG) and a rhombus metal structure is presented and experimentally demonstrated. By heating low softening point glass via a micro torch, the polyimide-coated FBG could be fixed into the rhombus metal structure. Consequently, when the rhombus structure is stretched and compressed, respectively, then the FBG will be subjected to a reverse state. Moreover, the strain sensitivity is controllable and enhanced by adjusting the dimension of the rhombus metal structure appropriately. The experiment was then carried out by using an equi-intensity cantilever beam and high temperature chamber, and the result showed that the proposed high temperature strain sensor could be used at the high temperature of 300°C. A resolution of ∼10 με has been experimentally achieved. The average wavelength strain sensitivity at 300°C is 1.821 and 1.814 pm/με, for the compressed and stretched states, respectively.

A Review of Coating Materials Used to Improve the Performance of Optical Fiber Sensors

“…The fabrication is similar to that in [ 35 ], where the F-P sensor based on SMF was used again. The sensors of Figure 20 were tested in [ 90 , 91 ], where the difference is that the sensor was used to measure the temperature and refractive index in [ 81 ], while it was used to measure temperature and pressure in [ 91 ]. This fully shows the potential of UV-curable polymer in fiber sensing.…”

“…In [81], an FBG coated with polyimide was installed in the rhombus metal structure; the relative positions of FBG and rhombus are shown in Figure 16. The sensor was used for the strain at a high temperature, and the function of polyimide was the stability sensing performance [81], which is the same as that in [75]. In [81], an FBG coated with polyimide was installed in the rhombus metal structure; the relative positions of FBG and rhombus are shown in Figure 16.…”

Sensitivity Enhancement of FBG-Based Strain Sensor

“…Comparing to existing FBG-based strain sensors in References [ 20 , 21 , 22 , 23 , 24 , 25 ], the particular mechanical configuration in this paper brings lots of advantages to the designed sensor. Firstly, the proposed sensor has a small and compact structure, which make it possible to apply it in regular-sized mechanical equipment.…”

“…Additionally, some other researchers utilized substrates with flexure hinges to enlarge the strain at the FBG area. Zhang et al [ 22 ] presented a diamond-frame packaged FBG strain sensor, which was temperature-insensitive and the strain sensitivity was enhanced to 1.814 pm/με. Guo et al [ 23 ] used a substrate with flexure hinges to improve the strain sensitivity of a FBG-based sensor.…”

“…The dynamic working range is an important parameter of a strain sensor. However, References [ 20 , 21 , 22 , 23 ] do not provide this property as they are used for static or quasi-static strain measurements. Through the finite element method, Nawrot et al [ 24 , 25 ] analyzed the resonant frequency of their sensor.…”