Akbar Ranjbar, Mohammad-Ali Saeimi-Sadigh, Bashir Behjat*
The Journal of Mechanical Science and Technology, vol. 25, no. 3, pp.605-611, 2011

Abstract : Condenser microphones are widely used in electronic and acoustic applications. Although, various mechanical and electro-mechanical methods have been developed to design and analyze these sensors. However, due to the difficulty of fluid-structural-electrical couplings, none of them can introduce a method that consider all parameters of the design together. This research concerns the effects of four main parameters: a) Air gap size; b) Number of holes on the back-plate; c) holes radius size and d) location of the holes in back plate, on the response of the microphones. This analysis have been carried out based on coupled finite element and finite volume method using ANSYS-CFX software to simulate fluid-structure interaction between the diaphragm and air in the air-gap region. By using this method, the effects of the geometric parameters on the response of the microphone have been investigated. Results show that, increasing air gap size, holes radius, and holes number decrease the damping effects of the air between diaphragm and back plate. On the other hand, increasing the distance between the holes has the opposite effect. In addition, results reveal that among these four parameters, increasing the number of holes on back plate is the most efficient method in reducing air-gap damping effects.

Keyword : Condenser microphone; ANSYS-CFX; Finite element methods; Fluid structure interaction