A novel Fiber Bragg Grating strain sensor based on rhombus structure at high temperature

Due to the distinctive merits of FBG, e. g., compact size and immune to electromagnetic, strain sensors based on FBG have attracted an increasing number of attentions in the field of structural health monitoring. But it is not easy to fabricate a strain sensor which can survive at high temperature, because normal material can not stand in a strain creep when the temperature is higher than 200 degrees C. In this paper, a novel strain sensor consisting of a high temperature resistant FBG and a metal rhombus structure is presented and demonstrated for surface strain measurement. The FBG is bonded on the metal structure via a low softening point glass and pre-stretched about 2nm before it is bonded, so it can measure compress and stretch tension. The experimental result shows that the proposed strain sensor can survive at 300., and the average wavelength-strain sensitivity for compress and stretch, are 1.821 pm/mu epsilon and 1.814 pm/mu epsilon, respectively. A more insensitive material to temperature and more appropriate adhesive are needed to improve the linear relationship in the next step.