Soil pressure sensor based on temperature compensation FBG

Since the present soil pressure sensors cannot be used to realize long term and real time monitoring, a temperature compensation FBG sensor is designed. Flat diaphragm with hard core is selected as elastic element, and a compact FBG with high sensitivity, wave division multiplexing and sensor network features is adopted as sensing element. Grating free of stress is used to compensate temperature. According to experiments and tests, the sensor has sensitivity of 1.5nm/MPa, linearity error of 0.35％, repetitiveness of 0.06％, delay of 2.19％ and static error of 2.21％, which meet the requirements of engineering application.