Ultrahigh-Sensitivity Accelerometer Enabled by EFPI and Deflection Amplification Structure

In this paper, an ultrahigh-sensitivity accelerometer incorporating an extrinsic Fabry-Perot interferometer (EFPI) and deflection amplification structure is proposed and experimentally demonstrated. The deflection amplification structure is constructed by a lever beam with cubic bead attached on the free end, and a buckled beam fixed at level beam midpoint. When exposed to acceleration, the lever beam vibrates, and force generated thanks to cubic bead gravity is greatly amplified and transferred to the connected buckled beam, which is finally converted into lateral displacement, thereby amplifying small displacement change at lever beam’s free end to one at the midpoint of buckled beam. And the amplified displacement is monitored by EFPI and full-spectrum demodulation algorithm. Theoretical and simulation analyses are applied to study the sensor response under vibration. Then the sensor is fabricated, and experiments are performed. Experimental results show that resonant frequency of the sensor is 368 Hz. In the flat frequency range of 10-200 Hz, the sensitivities at 100 Hz and 200 Hz are measured to be 11.118 μm/g and 8.075 μm/g, respectively. With the advantages of easy fabrication, ultrahigh-sensitivity and wide frequency bandwidth, the proposed accelerometer demonstrates great potential for structural health monitoring of power grid equipment.