Differences

This shows you the differences between two versions of the page.

--- team:gdeliege:mems [2015/08/12 14:25] – created geoffrey
+++ team:gdeliege:mems [2016/03/30 15:23] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-==== Micro Electro-Mechanical Systems ====
+===== Microelectromechanical systems =====
+=== Background ===
+I worked on a research project over microelectromechanical systems (MEMS)
+in the Aerodynamics group of Prof. Essers.
+This project was a collaboration between several research groups of the Université de Liège:
+Aerodynamics, Mechanical Vibrations (Prof. Golinval) and Applied and Computational Electromagnetics
+(W. Legros).
+My objective in this project was to simulate the deformation of microactuators
+taking into account the damping effect of air.
+These microactuators had to be manufactured by [[http://www.imtek.de/laboratories/mems-applications/mems_home?set_language=en|IMTEK]] and tested in the vibrations lab.
+=== Problem description ===
+I designed the geometry of the actuators together with Véronique Rochus and Guillaume Sérandour from the Mechanichal Vibrations group.
+The shape and dimensions of the actuators were strongly limited by manufacturing constraints.
+Therefore, we started with a microplate as suggested by IMTEK specialists.
+An example of such plates is shown in Fig. 1;
+although this is not represented in the drawing,
+the extremities of the beams are clamped so as to maintain the structure
+a few microns above the base of the chip.
+The square holes are imposed by the manufacturing process.
+The vibration of the plate is induced by the electric potential difference
+between the plate and the square electrode which is fixed to the chip.
+{{ :team:gdeliege:arc03.png?500 |}}
+//Figure 1. Geometry of the micro-actuator (length=300 $\mu m$ , width=100 $\mu m$ , thickness=2 $\mu m$ ). The aluminium plate is 2 $\mu m$  above the electrode.//
+=== Numerical simulations ===
+My first task was to design an automated way to calculate the mesh deformation of the air domain
+when the actuator moves.
+The difficulty was to keep an acceptable aspect ratio of the deformed mesh elements, which was of course critical between the plate and electrode.
+I also had to couple the different programs needed to make the coupled simulations:
+  * a fluid dynamic finite volume software written in C by Didier Vigneron, parallelized with MPI (distributed memory);
+  * a mechanical finite element software, OOfelie, written in C++ by [[http://www.open-engineering.com/|Open Engineering]];
+  * a C++ code of my own, which calculated the electrostatic force and the mesh deformation.
+An external script called the different codes in turn and converted the input/output files to ensure data compatibility.
+Fig. 2 shows results of the electric simulation on a quarter of the plate.
+Electromechanical simulations were performed at different excitation frequencies (Fig. 3, left) and a full electromechanical-fluid simulation was made at the resonance frequency (Fig. 3, right).
+{{ :team:gdeliege:arc01.png |}}
+//Figure 2. Electric scalar potential and electric force acting on the plate, calculated with my own code (mesh and visualization with [[http://www.geuz.org/gmsh|Gmsh]]).//
+{{ :team:gdeliege:arc02.png |}}
+//Figure 3. Vertical displacement of the plate : (left), electromechanical simulation (OOfelie+my code) for an excitation frequency equal to  $0.5\,\nu_r$ ,  $\nu_r$  and  $2\,\nu_r$ , where  $\nu_r$  is the resonance frequency; (right), electromechanical simulation with/without fluid coupling (OOfelie+my code+Didier Vigneron's code) at the resonance frequency.//
+\\
+\\
+[[team:gdeliege|Back to main page]]