[Back]

D. Tumpold, M. Kaltenbacher, C. Glacer, M. Nawaz, A. Dehé:
"Modeling Methods of MEMS Micro-Speaker with Electrostatic Working Principle";
Poster: SPIE Microtechnologies 2013, Grenoble, France; 2013-05-24 - 2013-05-26; in: "Proceedings of SPIE Microtechnologies 2013", Smart Sensors, Actuators, and MEMS VI, SPIE Vol. 8763, 876324, Grenoble (2013), ISBN: 978-0-8194-9565-5; 1 - 12.

The market for mobile devices like tablets, laptopsor mobile phones is increasing rapidly. Device housings get thinner
and energy efficiency is more and more important. Micro-Electro-Mechanical-System (MEMS) loudspeakers,fabricated
in complementary metal oxide semiconductor (CMOS) compatible technology merge energy efficient drivingtechnology
with cost economical fabrication processes. In mostcases, the fabrication of such devices within the design process is a
lengthy and costly task. Therefore, the need for computer modeling tools capable of precisely simulating the multi-field
interactions is increasing. The accurate modeling of such MEMS devices results in a system of coupled partial
differential equations (PDEs) describing the interaction between the electric, mechanical and acoustic field. For the
efficient and accurate solution we apply the FiniteElement (FE) method. Thereby, we fully take the nonlinear effects
into account: electrostatic force, charged moving body (loaded membrane) in an electric field, geometric nonlinearities
and mechanical contact during the snap-in case between loaded membrane and stator. To efficiently handle the coupling
between the mechanical and acoustic fields, we apply Mortar FE techniques, which allow different grid sizes along the
coupling interface. Furthermore, we present a recently developed PML (Perfectly Matched Layer) technique, which
allows limiting the acoustic computational domain even in the near field without getting spurious reflections. For
computations towards the acoustic far field we us a Kirchhoff Helmholtz integral (e.g, to compute the directivity
pattern).
We will present simulations of a MEMS speaker system based on a single sided driving mechanism as wellas an outlook
on MEMS speakers using double stator systems (pull-pull-system), and discuss their efficiency (SPL) and quality (THD)
towards the generated acoustic sound.

MEMS, finite element modeling, speaker, array, nonlinearities, acoustics, mechanics, Kirchhoff Helmholtz integral

http://dx.doi.org/10.1117/12.2016468