Low-frequency FBG vibration sensors for micro-seismic monitoring

Vibration sensors are key components in low-frequency micro-seismic monitoring, and their performance directly determines the accuracy of monitoring results. In response to the current problem that fiber Bragg grating (FBG) vibration sensors are difficult to effectively monitor micro-seismic low-frequency vibration signals, a rigid L-shaped beam FBG vibration sensor based on bearings is proposed. Firstly, a sensor model is established and theoretically analyzed; secondly, key parameters are optimized using differential evolution algorithm and imported into COMSOL simulation software for static stress analysis and dynamic characteristic analysis; finally, the sensor prototype is developed and a low-frequency vibration test system is set up to verify the sensor performance. The results reveal that the inherent frequency of the sensor is 57 Hz, with a flat response band of 0.3-35 Hz, a frequency lower limit of 0.05 Hz, a transverse interference degree of 4.5%, an average sensitivity of over 800 pm g(-1), a dynamic range of 67.75 dB, favorable linearity, and the ability to achieve temperature self-compensation. Research findings provide new insights into low-frequency micro-seismic monitoring.