Miniaturized fiber optic accelerometer incorporating liquid metal as the proof mass

The inertial element of a solid block is commonly used as the proof mass in traditional accelerometers. However, it is challenging to accommodate both the high-density solid-state proof mass and the highly elastic component simultaneously in a miniature sensor, which makes it difficult for the sensors to maintain comparable sensing performance at a miniaturized size. Here, a novel, to the best of our knowledge, liquid metal-based fiber optic accelerometer (LMFOA) is proposed for the first time to meet this requirement. A theoretical model for the LMFOA is introduced to illustrate its feasibility and sensing mechanism. Then, a miniature LMFOA based on a gallium-indium-tin alloy and a polymer-based flexible diaphragm is demonstrated experimentally, showing excellent consistency between the simulation and experimental results. The characteristic test results indicate that the prepared LMFOA has an acceleration sensitivity of 36.6 dB re 1 rad/g below 300 Hz, with a transverse cross talk less than -35 dB. By integrating high-density, highly fluidity liquid metal with a highly flexible diaphragm, the LMFOA shows great potential for applications requiring miniaturization.