Characterization of the MEMS directional sound sensor fabricated using the SOIMUMPs process

Abstract

A micro-electro-mechanical system (MEMS) based directional sound sensor performance is characterized. The operation of directional sound sensor is based on the hearing organ of Ormia ochracea fly, which uses coupled bars hinged at the center to achieve the directional sound sensing. The MEMS sensor design considered in this thesis is fabricated using a process by which the sensor has two resonant vibrational modes: rocking and bending. The sensor is simulated using finite element analysis and tested by actuating the sensor using a sound stimulus. An analysis is undertaken to describe, in mathematical terms, the relationship between the sensor's amplitude of vibration and various parameters such as the angle of incidence, frequency and the intensity of sound. The experimentally-observed vibrational frequencies are found to be in good agreement with the simulated data, which supports the use of the simulation in future sensor development. The observed amplitudes of vibration are significantly greater than those of sensors fabricated with the process used in previous studies. The relationship between the amplitude of vibration and the incident angle are found to agree with the theoretical predictions. The results indicate that it is possible to fabricate miniature sound sensors that mimic the fly's hearing system.