Small-size magneto-mechanical resonators (MMR) represent an emerging class of passive, wireless sensors that combine a sensing functionality with a tracking option. Their operation principle is based on a resonating rotor oscillation whose frequency is defined by the magnetic flux density of a stator magnet, and one general sensing mechanism is the coupling of an external parameter to this resonator frequency. In this study, the authors investigate an approach for encoding temperature information as a shift in the natural oscillation frequency, making use of the temperature-dependent magnetic properties of gadolinium (Gd).
An isolated simulation study was performed on the temperature scaling of the magnetic field generation for stators coated with gadolinium of varying thickness. The results show that the magnetic phase transition of gadolinium at its Curie temperature leads to a pronounced change in the magnetic permeability, which enables a significant magnetic shielding behaviour only for lower temperatures.
In the transition regime, the authors find a peak sensitivity reaching 45.8 hertz per kelvin, which exceeds existing values from the literature by up to a factor of about 20. The findings of this work are an important step towards quantitative temperature extraction with high sensitivity using magneto-mechanical resonators.
The study is a collaboration between the Section for Biomedical Imaging at the University Medical Center Hamburg-Eppendorf, the Institute for Biomedical Imaging at Hamburg University of Technology and the Fraunhofer Research Institution for Individualized and Cell-based Medical Engineering IMTE in Lübeck, and was presented at the IEEE SENSORS 2025 conference in Vancouver, Canada.
Jonas Faltinath, Miriam Schmitz, Fynn Foerger, Martin Möddel, Tobias Knopp (2025). Simulating Gadolinium-Induced Magnetic Field Variations for Temperature Sensing with Magneto-Mechanical Resonators. 2025 IEEE SENSORS, 1-4.
