Toky RABENIMANANA : "Modeling, fabrication and experimental characterization of weakly coupled MEMS arrays for the mass detection"

Toky RABENIMANANA PhD works : "Modeling, fabrication and experimental characterization of weakly coupled MEMS arrays for the mass detection"

Abstract : A study on mass microsensors using Anderson localization is conducted in this thesis. Different ways allowing to enhance their performances are proposed and demonstrated through two MEMS devices. Both devices use the same system composed of two mechanically coupled cantilevers, but the vibrations are generated in two different ways: the first device is actuated with an attractive electrostatic force while the second device is actuated with a repulsive electrostatic force. In order to get rid of initial imbalance due to manufacturing defects, the electrostatic softening effect is used by tuning the DC voltage of the actuation. For the first device, a concept with an asymmetric system including two cantilevers of different lengths is proposed. We thus reduce the effective stiffness of the short cantilever to balance the system. With the second type of actuation, the weak electrostatic softening effect forces us to use two microbeams of the same length. But the system is still balanced with the same approach. Thanks to the functionalization of electrostatic nonlinearities, the first device shows an enhanced sensitivity, which is 67% higher than the maximum sensitivity reachable in the linear regime. Concerning the second device, it
shows the absence of electrostatic nonlinearities, which allows to increase the linear dynamic range by up to 70% of the gap. It should improve not only the mass resolution of the sensor, but also the accuracy of the mass sensing. All of these concepts are first theoretically investigated with the developed analytical model based on the Euler-Bernoulli beam theory. They are then experimentally demonstrated after the sensors are manufactured with the MUMPS.

Jury composition : Joseph LARDIES Professeur Université Bourgogne - Franche-Comté, PhD Director

Najib KACEM, Maître de conférences, Université Bourgogne - Franche-Comté, PhD Co-director

Vincent WALTER, Maître de conférences, Université Bourgogne - Franche-Comté, PhD Co-director

Sébastien HENTZ, Directeur de recherche, CEA, Laboratoire d’électronique et de technologie de l’information (LETI), Reporter

Claude-Henri LAMARQUE, Professeur ENTPE, Université de Lyon, Laboratoire de Tribologie Dynamique des Systèmes (LTDS), Reporter

Jérôme JUILLARD Professeur, Centrale Supélec Génie électrique et électronique de Paris (GEEPS)? Reviewer

Skandar BASROUR Professeur, Université Grenoble Alpes, Laboratoire Techniques de l'Informatique et de la Microélectronique pour l'Architecture des systèmes intégrés (TIMA), Reviewer

Localization : Amphithéâtre JJ Gagnepain, Institut FEMTO-ST - 15 B, Avenue des Montboucons, Besançon