Researchers: Virpi Junttila, Tommi Peussa, Jarmo Hietanen and Kimmo Kaski
This research is a combination of three projects: "Modelling and applications of the micromechanical systems in acoustics" and "MEMS simulations", both financed by the Academy of Finland, and "MIKSU technology program", which is partially funded by TEKES (National Technology Agency).
One part of this research is MEMS related fluid-structure interaction, and its core consists of the coupling between the mechanical structure and the fluid, more specifically gas. Here attention is paid to the velocity field produced by moving structures, and to the damping of the displacement due to gas viscosity, see Figure 38. The modelling of these phenomena is done analytically, if possible, and using several numerical tools, such as Ansys (ANSYS, Inc.), Femlab (Math Works), and especially Elmer, the last developed by CSC.
Since in microelectromechanical systems internal flow field is related to the internal energy consumption of the device, there is a need to optimize the device structure. In non-optimized design, for instance, vortexes of fluid can be produced. If this can be avoided with more optimized design, the transducer will achieve higher performance.
Also the optimal design of perforated and corrugated membranes are studied by using numerical methods (e.g. Ansys). The number and positions of holes affect the frequency range of the vibrating membrane, see Figure 38.
|Figure 38: Studies of MEMS structures. On the left: Pressure field derived from Navier-Stokes equations for compressible fluid around a vibrating plate on top of a cavity (simulation done with Elmer). On the right: Displacement of a vibrating annular plate (Simulation done with Ansys).|
Some related studies are made in collaboration with VTI Hamlin, Center of Scientific Computing (CSC), Nokia Research Center, Vaisala Oyj and VTT Electronics.