MEMS polymumps-based miniature microphone for directional sound sensing

Abstract

A miniature directional sound sensor was fabricated using micro-electromechanical system (MEMS) technology based on the operational principle of Ormia ochracea fly's hearing organ. The fly uses coupled bars hinged at the center to achieve the directional sound sensing by monitoring the difference in vibration amplitude between them. The MEMS sensor design employed in this thesis was fabricated using the PolyMUMPs process. The sound sensor has two primary vibrational modes (rocking and bending) which were simulated by finite element analysis and tested by actuating the sensor using both electrostatics and sound. The experimentally observed vibrational frequencies were found to be in good agreement with that of the modeling but the amplitudes of vibration were found to be relatively small compared to the expected values. The design of optimized sensors, with larger amplitude of vibration hence high sensitivity, will be discussed in this presentation.