An Integrated MEMS Magnetic Gradiometer Rejecting Vibrations and Stray Fields

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Author
Gasparin, Enrico
Hoogerwerf, Arno
Bayat, Dara
Spinola Durante, Guido
Petremand, Yves
Tormen, Maurizio
Despont, Michel
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Abstract
Due to electrification, magnetic sensors are increasingly deployed in magnetically polluted environments. To reject stray fields, differential sensing schemes are typically used. In this paper, we rely instead on a single-point gradiometric sensing scheme based on the force exerted on a magnet, which is directly related to the magnetic field gradient. Unlike the prior art, our concept uses a differential MEMS force-sensing mechanical transducer. The overall sensor rejects not only magnetic stray fields, but also mechanical disturbances such as vibration and gravity. It is the first single-point MEMS gradiometer that can operate unshielded in various orientations. Our prototype realization achieves a noise density of 4 nT/mm/√Hz in a ±300 μT/mm measurement range. We demonstrate its operational effectiveness in a bus-bar current sensing application. Finally, the paper discusses the remaining weaknesses and provides an outlook for MEMS-based magnetic sensors.
Publication Reference
ESSERC 2024 Conference, Bruges, Belgium 9-12 September 2023
Year
2024-09-09
Sponsors
InnoSuisse