Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 49: Magnetic Imaging, Information Technology, and Sensors
MA 49.4: Talk
Thursday, March 12, 2026, 15:45–16:00, POT/0112
Magneto-Mechanical Resonator with Stimulus-Responsive Hydrogel for pH Sensing — •Nora Timm1, Jonas Faltinath2,3, Bruno Kluwe1, Jonas Schumacher1, Pascal Stagge1, and Tobias Knopp1,2,3 — 1Fraunhofer Research Institution for Individualized and Cell-based Medical Engineering IMTE, Lübeck, Germany — 2Section for Biomedical Imaging, University Medical Center Hamburg-Eppendorf, Hamburg, Germany — 3Institute for Biomedical Imaging, Hamburg University of Technology, Hamburg, Germany
Magneto-mechanical resonators (MMRs) offer a promising platform for passive and wireless sensing. We present a novel chemical sensor by integrating a miniaturized MMR (2 mm × 2 mm × 7 mm) with a pH-responsive poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel functionalized with acrylic acid. In our implementation, the stimulus-responsive hydrogel modulates the distance between two permanent magnets through reversible volumetric changes in response to pH variations. One magnet serves as the stator and the other as the rotor of the MMR that is excited into torsional oscillations by external magnetic fields. Since the resonance frequency depends on magnet separation, frequency analysis of the inductively detected signal enables pH sensing. We demonstrate the sensor’s response to pH variations in the range of pH 5-7 with observable shifts in resonance frequency of more than 40 Hz, which corresponds to a relative shift of more than 12 %. This proof-of-concept establishes hydrogel-integrated MMR sensors as a viable approach for wireless chemical sensing.
Keywords: magneto-mechanical resonator; MMR; pH-sensing; stimuli-responsive hydrogel