Design and Finite Element Analysis of a MEMS Capacitive Microphone

Microphone is a sensor that converts audio to an electrical signal. Electromagnetic converters simplify converting audio to electromagnetic signals. Microphones are widely used in telecommunication tools, hearing aid systems and protection applications. Most of the nowadays microphones utilize electromagnetic induction (dynamic microphones), capacitance change (capacitive microphones) or piezoelectricity (piezoelectric microphones) in order to produce electrical signal from air pressure changes. Micro-electro-mechanical system (MEMS) microphones have a great significance in recent years due to their small size, low power consumption and high sensitivity. Among different types of MEMS microphones, capacitive microphones are of great importance as they have higher sensitivity, signal to noise ratio (SNR) and stability. In this article, first functions of MEMS microphones are presented in introduction and then, design process of a capacitive MEMS microphone is discussed. For enhancing sensitivity of the reviewed microphone, a new structure is proposed. This new structure has more holes and thicker diaphragm in comparison with the primary structure. Furthermore, in order to compensate mechanical sensitivity reduction due to creating more holes that decreases whole mass of diaphragm, nickel is used instead of aluminum as it has higher density. For finite element analysis (FEA) of proposed structure, Ansys Multiphysics Utility Tool 16.0 is utilized. Simulation results indicate that mechanical sensitivity of proposed capacitive MEMS microphone is 30 nanometers per Pascal.

کلیدواژه ها:

Micro-electro-mechanical system ، capacitive microphone ، porous diaphragm ، Finite element analysis