Integrated Systems and Photonics

Magnetic field sensors

In cooperation with the Institute for Materials Science, the Institute of Physical Chemistry and the Faculty of Medicine, we develop and explore novel, highly-sensitive magnetic field sensors, primarily for use in the non-invasive diagnosis of cardiac function (magnetocardiogram, MCG) as well as brain function (magnetoencephalogram, MEG). The required sensitivity in the picotesla to femtotesla range should be achieved by sensor networks made from novel composite material, which can be operated at room temperature. In contrast, the currently-used SQUID (superconducting quantum interference device) sensors require cooling as well as extensive shielding measures.

Since the conversion efficiency from the magnetic field to the electrical signal is too low for known single-phase materials (e.g. Hall effect, magnetoresistive), composites of magnetostrictive and piezoelectric materials are being investigated. The magnetic field creates a strain on the magnetostrictive material, which is transferred to the piezoelectric material, where it generates measurable charges and electrical potentials. An example of this so-called product characteristic can be seen in the layer structure shown in Figure 1 made of magnetostrictive (MS) and piezoelectric (PE) layers. An oscillating magnetic field generates an oscillating electrical potential. If the magnetic field instigates mechanical resonance, this causes significantly amplified signals.

Abbildung 1:
Figure 1: Magnetic field sensor consisting of a magnetostrictive (MS) and a piezoelectric (PE) layer on a silicon bending beam.
Abbildung 2:
Figure 1: Magnetic field sensor consisting of a magnetostrictive (MS) and a piezoelectric (PE) layer on a silicon bending beam.


Our part of the joint research activity is modelling the electrical, magnetic and mechanical properties of different sensor types. As such, we currently simulate PE-MS composite sensors and sensors based on surface acoustic waves (SAW). We develop analytical models and utilise the finite element method (e.g. COMSOL Multiphysics). Research topics include strain, electric and magnetic field distributions and electrode placements on sensors, resonance effects, and the influence of geometry and material selection. We investigate miniaturised sensors and sensor arrays.

The Collaborative Research Center 1261 is funded by the German Research Foundation (DFG).


Selected Publications

A. Kittmann, P. Durdaut, S. Zabel, J. Reermann, J. Schmalz, B. Spetzler, D. Meyners, N. X. Sun, J. McCord, M. Gerken, G. Schmidt, M. Höft, R. Knöchel, F. Faupel, and E. Quandt, "Wide Band Low Noise Love Wave Magnetic Field Sensor System", Sci. Rep., vol. 8, no. 1, pp. 1–10, (2018). 
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J. L. Gugat; M. C. Krantz; J. Schmalz; M. Gerken, "Signal-to-Noise Ratio in Cantilever Magnetoelectric Sensors", IEEE Transactions on Magnetics, vol. 52, no. 9, pp. 7005005 (2016). 
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M. Gerken, "Resonance line shape, strain and electric potential distributions of composite magnetoelectric sensors", AIP Advances 3, 062115 (2013), Issue 6 (2013)
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