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T. Huber:
"Sensoranwendungen für amorphe weichmagnetische Materialien";
Betreuer/in(nen), Begutachter/in(nen): D. Süss, F. Keplinger; Institut für Festkörperphysik E138, 2015; Rigorosum: 07.04.2015.

The first part of this work is dedicated to acustomagnetic sensors. These, also known as magnetoelastic resonance sensors, consist of at least one softmagnetic ribbon and an adjacent bias magnet. The biasmagnet is used to define the working point of the resonator, as the mechanical resonance frequency depending on external magnetic fields is very strong. For a better understanding of the resonators a mathematical model was developed. It was possible to describe the dependency of the mechanical resonance frequency of two coupled resonators successfully with this model. This thesis deals with temperature threshold sensors on the basis of such magnetoelastic resonance sensors. When reaching a temperature threshold the sensor response frequency (resonance frequency) should be shifted irreversible by an amount which is as big as possible. To obtain such a behavior a system consisting of some movable magnetic materials is used. When their position is changed the effective strayfield changes the resonance frequency. The second concept describes a sensor using the harmonic response generated by the magnetization process of soft magnetic materials to obtain a possibility to distinguish between different sensors. A sinusoidal magnetic field is produced by a coil to magnetize a softmagnetic ribbon periodically. A compensated pick-up system measures the magnetization of the ribbon. Doing a Fourier transformation with the gathered signals leads to a harmonic spectrum, which contains informations about the material, the geometric relations and the static magnetic field acting on the ribbon. The concept was mathematically described and so the dependencies of the system for some parameters determined. Also a coffee machine produced by a well known company was rebuilt as a prototype for capsule recognition. A set of three flavors with three capsules each was constructed and successfully tested.