Low-frequency fiber Bragg grating accelerometer based on a dual-hinge series structure

This paper proposes a compact Fiber Bragg Grating (FBG) accelerometer with a series double-hinge structure for low-frequency vibration sensing. Under external excitation, the coupled deformation of the upper and lower hinge segments enhances strain transfer efficiency and improves the sensor’s response in the low-frequency range. A two-degree-of-freedom theoretical model was established to investigate the resonant characteristics and sensitivity of the accelerometer, and its structural properties were verified through finite element simulation. Experimental results show that the sensor has a resonant frequency of approximately 84 Hz, an effective operating range of 0.5–50 Hz, and a sensitivity of 103.05 pm/g. Furthermore, the sensor exhibits excellent linearity, with an R 2 value of 99.96% and the cross-axis responses along the x - and z -directions are 10.8 and 6.4%, respectively, relative to the y -axis sensitivity.