Modeling of an electrostatically actuated microelectromechanical (MEMS) speaker system

The market for tablets, laptops and mobile devices is increasing rapidly. Device housings get thinner and energy efficiency plays a major role for battery-powered devices. Microelectromechanical (MEMS) loudspeakers, fabricated in complementary metal oxide semiconductor (CMOS) compatible technology merge energy efficient driving technology with cost economical fabrication processes. Fabricating these devices is a elaborating and expensively task. Therefore, the need of computer models, capable of precisely simulating the multi-field interactions is strongly increasing. We use a system of coupled partial differential equations (PDEs) describing the interaction between the electrostatic, mechanical and acoustical field and apply finite element method FEM to solve them. Additionally, we fully take nonlinear effects like large deformations or stress stiffening effects into account. Mortar FEM is used, to efficiently handle the coupling between mechanical and acoustical field. In combination with special boundary conditions, like perfectly matched layers (PML) truncated propagation regions can be applied in the model. We will present simulations of a MEMS speaker system based on a single sided driving mechanism starting at the electric potential applied on the two electrodes and resulting in the generated sound pressure level (SPL).