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D. Tumpold, M. Kaltenbacher:
"Modeling Methods of MEMS Speaker Devices with Electrostatic Driving Principle.";
Talk: ANSYS Conference & 31. CADFEM Users´ Meeting 2013, Mannheim, Germany (invited); 2013-06-19 - 2013-06-21; in: "ANSYS Conference & 31. CADFEM Users´ Meeting 2013", ACUM 2013, (2013), ISBN: 3-937523-10-3; 1 - 12.

This paper presents a MEMS loudspeaker system based on an electrostatic working principle. The
first section deals with the function of the singleended driving technology and gives a brief outlookon
the push-pull or pull-pull driving technology with its advantages and disadvantages. The focus of the
paper is on modeling the electrostatic-mechanical coupling of the transducer, starting at an applied
voltage resulting in a mechanical movement. The electrostatic-mechanical model is fully coupled with
native ANSYS. Structural nonlinearities as large deformation or stress stiffening effects due to various
layers are taken fully into account. Since there are several methods to model the electrostatic force
interacting with the mechanical structure, two commonly used techniques are presented. The first
modeling ansatz uses an electro mechanical transducer (EMT) element, the TRANS126. In this
method the electrostatic force is represented by a reduced order line element. Advantages and
disadvantages of this method are compared with the second possibility, the multi-field ansatz. In the
multi-field ansatz, the transducer is split up into two physical fields. First the electrostatic field and
second the structural field, where the interaction between both fields is realized with fluid structural
interface (FSI) boundary conditions. We used sequentially coupling with conservative load transfer.
Both modeling methods are compared to an analyticalansatz derived from virtual work principle. The
analytical ansatz includes the Coulomb force as well as the interface force between insulation layer
and air.
The last part of this paper describes the advantages and disadvantages of both models including their
contact behavior in snap-in case.

MEMS, CMOS, transducer, speaker, modeling, electrostatic, force, structural mechanics, multi-fields, virtual work principle, TRANS126, nonlinear