An FBG-Based Liquid Pressure Sensor Integrated with Flange Cylinder

Abstract

In this work, a liquid pressure sensor is proposed by encapsulating the fiber Bragg grating (FBG) inside the flanged cylindrical structure with the polydimethylsiloxane (PDMS) elastic material. Due to the tight binding of the PDMS polymer to the fiber surface, the proposed sensor is able to convert the external liquid pressure into the longitudinal strain on the FBG, resulting in a shift of the central Bragg wavelength. Through the experimental verifications, it can be observed that the hydraulic sensitivity of sensor with the inner diameter of flange cylinder of 15mm in the range of 0 to 30m water level is about 4.417 nm/MPa, which is 1472 times of the bare FBG sensitivity. Since the FBG is located inside the flange cylinder, the sensor can greatly reduce the impact of external environment effects on FBG and plays a great protective role on the FBG. In addition, the new developed sensor has many excellent properties such as high linearity (about 99.65%), stability and simple manufacturing, and can be used for long-term and stable monitoring of hydraulic pressure or water level.