An FBG Temperature–Pressure Sensor Based on Diaphragm and Special-Shaped Bracket Structure

A fiber Bragg grating (FBG) sensor capable of simultaneous temperature–pressure measurement is presented and experimentally verified, which consists of a diaphragm, a special-shaped bracket, dual FBGs, and protective housing. The principle of simultaneous temperature and pressure measurement with dual FBGs is theoretically illustrated and simulated by a finite-element analysis. The experimentally investigated results demonstrate that the sensor can be employed to measure temperature and pressure in environments where the temperature ranges from 50 °C to 200 °C and the pressure ranges from 0 to 40 MPa. The temperature sensitivity of the sensor is 31.8 pm/°C with a linear correlation coefficient of 0.9997; the pressure sensitivity is 50.6 pm/MPa, the linearity is 0.21%, and the repeatability and hysteresis error are 0.024% and 0.16%, respectively. The sensor exhibits a large measuring range, high-temperature resistance, miniaturized structure, and easily multiplexed, which allows it for temperature and pressure dual parametric measurements in high-temperature and high-pressure environments such as oil and gas wells.