Title: Particle detection in liquids with piezoelectric MEMS resonators
Language: English
Authors: Schlögl, Matthias 
Qualification level: Diploma
Keywords: MEMS Resonators; Cantilever; Piezoelectricity
Advisor: Schmid, Ulrich 
Assisting Advisor: Patocka, Florian 
Issue Date: 2018
Number of Pages: 56
Qualification level: Diploma
In this thesis a cantilever based MEMS resonator is presented to detect micro- and submicrometer sized magnetic particles in liquids, such as wear debris in oil during engine operation (online measurement). The excitation is based on an integrated piezoelectric aluminium nitride layer. The frequency response spectrum of the cantilevers is optimized to excite roof tile modes, which are especially suitable for measurements in liquids because of the lower damping effects compared to pure out-of-plane modes. A planar coil-like structure is used to create locally a tailored magnetic field to attract magnetic particles to the cantilevers surface. This results in a change of the effective mass and a change in the resonance frequency of the mode under investigation. Based on finite element method simulations of the magnetic field distribution for several planar coil designs, different cantilever based sensor elements are designed and manufactured applying standard silicon micromachining. The resonance response behavior of the sensor elements are optically measured with a Laser Doppler vibrometer and tested with different particle sizes and compositions under laboratory conditions.
URI: https://doi.org/10.34726/hss.2018.52626
DOI: 10.34726/hss.2018.52626
Library ID: AC14555632
Organisation: E366 - Institut für Sensor- und Aktuatorsysteme 
Publication Type: Thesis
Appears in Collections:Thesis

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