Design of Piezo-Resistive Type Acoustic Vector Sensor using Graphene for Underwater Applications

Abstract

In recent years as the level of radiated noise of submarine drastically got decreased, the requirement of underwater acoustic sensor has become essential for the detection of low frequency acoustic signal. The latest advancement in the field of underwater sensors is the Micro Electro Mechanical Systems (MEMS) sensor. The major advantage of this sensor being determination of directionality along with the measurement of pressure of an acoustic signal. The biological inspiration behind the design of the sensor was derived from fish lateral line sensing system, with piezoresistive transduction principle to obtain the objective of miniaturization and low frequency signal detection. In this paper, we are reporting the design, simulation of an underwater two-dimensional MEMS acoustic vector sensor which exhibits better sensitivity, flexibility when compared to the traditional acoustic vector sensor. In this work, thin film of piezoresistve material, Reduced Graphene Oxide (Rgo) is taken as pressure sensing element instead of traditional polysilicon material and its performance in terms of sensitivity and directivity is analysed. MEMS acoustic vector sensors using Reduced Graphene Oxide and polysilicon were simulated on flexible kapton and silicon substrate respectively using COMSOL Multiphysics 5.5 vesrion. The simulation results indicates that designed vector sensor based on MEMS technology and piezoresistive effect of rGO on flexible kapton substrate is feasible and possesses better sensitivity of -149.47 dB when compared to the sensitivity of -171.37 dB of polysilicon based traditional acoustic vector sensor. The simulated value of eigen frequency of the sensor is found as around 47Hz, which almost matches with the theoretical value of resonance frequency of the sensor as per the design considerations of the sensor and hence capable of detecting low frequency acoustic signals.