Design of an Integrated MEMS Magnetic Gradiometer Rejecting Vibrations and Stray Fields
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Author
Hoogerwerf, Arno
Gasparin, Enrico
Bayat, Dara
Spinola Durante, Guido
Petremand, Yves
Tormen, Maurizio
Despont, Michel
Close , Gael
DOI
10.1109/JEDS.2025.3543662
Abstract
—Magnetic sensors are often used near current carrying wires or electrical motors generating significant mag netic interference. To mitigate the effects of these stray fields,
the traditional design approach relies on a differential sensing
scheme: multiple magnetometers are spaced apart, and the field
differences are measured. Despite being rejected, stray fields still
constrain the design space. Extra linear range and matched
channels are required to accommodate their peak amplitude
without saturation or residual common-mode leakage. On the
contrary, single-point MEMS gradiometers rely on the force
acting on a magnet, which is directly proportional to the
magnetic field gradient. The stray field is intrinsically rejected by
the magnetic transducing mechanism, even before entering the
measurement chain. The range of the measurement chain can
then be largely optimized for the gradient, independently of the
stray field amplitude. This paper discusses the design of a single point MEMS gradiometer. By design, it rejects magnetic stray
fields and mechanical disturbances like vibrations and gravity. It
is the first single-point MEMS gradiometer capable of operating
unshielded and in various orientations. The prototype achieves
a noise density of 4 nT/mm/√Hz within a measurement range of
±300 μT/mm. The paper demonstrates the sensor’s effectiveness
in a bus-bar current sensing application. Design limitations and
future design prospects are also outlined.
Publication Reference
JOURNAL OF ELECTRON DEVICES SOCIETY,
Year
2025
Sponsors
Melexis Technologies SA