Performance of cantilever-based piezoelectric

MEMS resonators in liquid environment

Institut: Elektrotechnik u. Informationste
Autor: Dipl.-Ing. Martin Kucera
ISBN: 9783903024533
Seitenanzahl: 204
Herausgeber: TU Verlag
Erscheinungsort: Wien 44

EUR 44,00

inkl. 10 % USt zzgl. Versandkosten

Art.Nr. 0099

Performance of cantilever-based piezoelectric

Performance of cantilever-based piezoelectric
MEMS resonators in liquid environment

Institut: Elektrotechnik u. Informationste
Autor: Dipl.-Ing. Martin Kucera
ISBN: 9783903024533
Seitenanzahl: 204
Herausgeber: TU Verlag
Erscheinungsort: Wien


Dissertation
Performance of cantilever-based piezoelectric MEMS resonators in liquid environment

zur Erlangung des Grades
des Doktors der technischen Wissenschaften
der Fakultät für Elektrotechnik und Informationstechnik
am Institut für Sensor- und Aktuatorsysteme E366
der Technischen Universität Wien


Abstract
In this work, piezoelectric-actuated MEMS (micro electromechanical systems) resonators are presented to study and optimise different mechanical vibration modes and their specific properties for monitoring the viscosity and density of liquid media. For this purpose, the mechanics of cantilevers as well as plate-type devices is introduced. They are fabricated using silicon micromachining in combination with sputter-deposited aluminium nitride.
The functional thinfilm material serves both for excitation of the specific vibration mode and for sensing purposes to determine the resonance frequency and the damping (Q-factor) by measuring the piezoelectrically generated charges as a change in the impedance spectrum.
The MEMS resonators are characterised predominantly in their fundamental in-plane vibration mode, as, in contrast to any out-of-plane mode, shear forces are transferred to a higher extend to the surrounding liquid media, thus favouring this mode for viscosity and density sensing. Especially the knowledge about the mode shape and the corresponding local distribution of the generated polarisation charges are of utmost importance for an optimised device operation. Basically, it turned out that a minimal mechanically strained surface area of the vibrating structure has to be covered with the piezoelectric layer to generate a technically exploitable measurement signal. In addition, a new class of vibration modes is investigated, showing a superior performance in the Q-factor and the level of the electrical output signal compared to commonly used vibration modes (e.g. out-of-plane, in-plane or torsional modes).
To evaluate the MEMS resonators under close to real life operation conditions a specific test setup is realised to control the liquid temperature up to 100°C. Furthermore, an electronic feedback circuit is realised allowing to enhance the Q-factor up to about a factor of 20 in air and up to about a factor of nine in ethanol, respectively.
The novel vibration modes and the design guidelines presented within the scope of this doctoral thesis will allow in the future to realise piezoelectric-actuated MEMS resonators based on cantilever or plate-type structures for measuring the viscosity and density in a widespread range of liquid media with a high sensitivity.

Dipl.-Ing. Martin Kucera


Dipl.-Ing. Martin Kucera

 

iBook anklicken


iBook Button


OPEN ACCESS anklicken



Open Access