A novel fiber Bragg grating pressure sensor with the smart metal structure based on the planar diaphragm

Abstract

This study develops a novel fiber Bragg grating (FBG) pressure sensor encapsulated with the smart metal structure. The smart metal structure sensor made of welding the FBG plating a gold coat and the nickel tube together using Au-Ge solder is introduced, and the FBG is mounted on a planar diaphragm to enhance the pressure sensitivity. The diaphragm can be pressurized along one axial direction, and responds to an axial force only. The FBG sensor pressure sensitivity is derived theoretically and validated experimentally. The measured pressure sensitivity of the shift in the Bragg wavelength of our experimental sensor is about 1.68×10^-4MPa^-1, which is approximately 85 times higher than that can be achieved with a bare FBG. The pressure measurement precision of 0.5% over a full measurement range of 20 MPa has been achieved. The linearity of our sensor is also good, and there is almost no hysteresis effect. The temperature compensation performance of the pressure sensor is also studied.