A Practical FBG Sensor Based on a Thin-Walled Cylinder for Hydraulic Pressure Measurement

A practical optical fiber sensor is proposed for hydraulic pressure measurement. A thin-walled cylinder is used as the sensing device, which will be deformed with the applied pressure. Two fiber Bragg gratings (FBGs) are used in the sensor probe. One is stuck on the outer wall of thin-walled cylinder along the circumferential direction to measure the deformation of the cylinder. The other FBG is stuck in the groove which is on the top of the thin-walled cylinder and acts as a temperature measurement device. The accurate pressure can be obtained by monitoring the difference of the two shifted Bragg wavelengths. Theoretical relation between the wavelength shift difference and pressure has been established by the theoretical analysis. Meanwhile, the experiments have been carried out to verify the feasibility. Experiment results show that the sensitivity of the proposed pressure sensor is 69.4 pm/MPa in the region of 0~16 MPa. Compared with other references, the proposed pressure sensor in this letter is more compact with good sensitivity and wide measurement range.