Three-Axis High-Sensitivity Vibration Sensor Based on Ultrafine and Ultrashort Fiber Bragg Gratings

This paper presents a three-axis high-sensitivity vibration sensor based on ultra-fine and ultra-short fiber Bragg gratings (FBGs). A theoretical model for the sensor's sensitivity and natural frequency is developed by deriving equations for steady-state torque balance. The effects of spring plate thickness, fiber diameter, and FBG packaging length on sensor performance are analyzed by this model. Results show that spring plate thickness has almost no impact, reducing fiber diameter improves sensitivity, and shortening FBG packaging length increases natural frequency. Therefore, based on the ultra-fine and ultra-short fiber Bragg gratings, the sensor is 3D modeled and fabricated. The performance of the sensor is verified through finite element analysis and experiments. The experimental results show that the natural frequencies of the sensor in X, Y, and Z directions are 466 Hz, 477 Hz, and 445 Hz, respectively, with a working frequency band of 0-300 Hz, and sensitivities of 2258.4, 2240.8, and 2274.2 pm/g, respectively. The linearity in the three-axis directions reaches R² = 0.9998, and the minimum acceleration resolution is about 95 μg. The sensor's performance, characterized by high sensitivity, wide bandwidth, and excellent three-axis consistency, offering valuable insights for high-sensitivity sensor designs.