Coupled D33 Mode-Based High Performing Bio-Inspired Piezoelectric MEMS Directional Microphone

Abstract

Microelectromechanical system (MEMS) directional microphones have been identified as having use in multi-projected virtual reality applications such as virtual meetings for projecting cameras. In these applications, the acoustic sensitivity plays a vital role as it biases the directional sensing, signal-to-noise ratio (SNR) and self-noise. The acoustic sensitivity is the multiplied outcome of the mechanical sensitivity and the electrical sensitivity. As the dimensions are limited in MEMS technology, the improvement of the acoustic sensitivity by reflecting the mechanical as well as electrical domains is a challenge. This paper reports on a new formation of the D33 mode, the coupled D33 mode, based on piezoelectric sensing to improve the acoustic functionalities. The unique advancement of the proposed D33 mode is that it allows multiple spans of the regular D33 mode to perform together, despite this increasing the diaphragm’s dimensions. At a reduced diaphragm size, the orientation of the coupled D33 mode realizes the maximum conversion of the mechanical deflection into electrical sensitivity. The significance of the proposed D33 mode in comparison to the regular D33 mode is simulated using COMSOL Multiphysics. Then, for a proof–of–concept, the experimental validation is carried out using a piezoelectric MEMS directional microphone inspired by the ears of the fly Ormia ochracea. In both ways, the results are found to be substantially improved in comparison with the regular approach of the D33 mode, showing the novelty of this work.