MODELING AND CHARACTERIZATION OF MEMS UNDERWATER ACOUSTIC SENSORS

Abstract

This project explores the application of existing micro-electro-mechanical systems (MEMS) acoustic sensors to lower-frequency, underwater domains. The sensors are configured as pressure-gradient microphones designed to operate near resonance, providing a dipole-like directional response while maintaining a higher signal-to-noise ratio (SNR) than conventional acoustic sensors. The goal of this thesis was to characterize these sensors in a new medium, which caused the frequency of operation to shift to lower values. Finite element simulation and laboratory and field experimentation were designed and executed to evaluate the sensor’s performance and survivability.This work proved that although the resulting sensors had lower sensitivity than in other media, this design is a viable option for underwater acoustic detection because it offers comparable performance with other researched underwater sensors while maintaining the designed directionality. Two of these sensors can be used in conjunction to form an acoustic vector sensor (AVS) with unambiguous 360 degrees coverage. Furthermore, the frequency range of operation is scalable by design, accommodating several different applications of naval interest. The continuity of this project can lead to the development of compact and directional underwater acoustic sensors.