Development of a High-Sensitivity and Adjustable FBG Strain Sensor for Structural Monitoring

In this paper, a new fiber Bragg grating (FBG) strain sensor with adjustable sensitivity is invented. The sensitivity adjustment, strain sensing, and temperature compensation principles of the sensor and the corresponding formulae are developed. The prototype sensor specimen is developed, and a series of tests are performed to investigate its strain sensitivity and temperature compensation characteristics. The results show that the strain sensitivity of the sensor can be adjusted effectively by the correspondent L/LFBG parameter, with an acceptable discrepancy within ±5% of the theoretical value. The linearity, repeatability, and hysteresis were analyzed, and the errors were 0.98%, 1.15%, and 0.09%, respectively, with excellent performance. When the temperature difference was 20°C, through temperature compensation calibration, the error between the monitored strain and the actual strain was within 5% after temperature compensation correction, showing that this new type of FBG strain sensor can meet the strain monitoring needs of various engineering structures and provide reliable data acquisition.