Minimal pressure masured based on magnetism

AMR sensors on flexible polyimide, sensor area: 770x1820 µm. (Photo: Christian Wittek/IMPT)

IMPT | Classical gas pressure cannot be measured in this way – but the deformation of an elastic membrane. A measurement based on magnetism is possible when hard magnetic particles are embedded in the membrane. This is proved by experiments made at the Institute of Micro Production Technology (IMPT).

IMPT investigates a novel method, which is based on magnetism, to specifically measure contact pressure. The system consists of a membrane, which possesses magnetic properties due to embedded hard magnetic particles.

When an external force deforms the membrane, the strength of the magnetic field emitted by the membrane changes with respect to a fixed geometrical point. Placing a magnetic field sensor at the geometrical point allows an indirect measurement of the applied force (and the pressure through the area). An elastomer (polydimethylsiloxane – PDMS) is used as the membrane elastomer in combination with hard magnetic particles; the sensor is an anisotropic magnetoresistive layer.

Preliminary experiments showed a linearly proportional change in intrinsic resistance with an increase of applied force, which shows that it is in principle possible to measure pressure and determine spatial distribution, when using several sensors.

by Maren S. Prediger

Image gallery for this article

  • AMR sensors on flexible polyimide, sensor area: 770x1820 µm. (Photo: Christian Wittek/IMPT)
  • AMR sensors embedded in polyimide with through-hole VIAS, designed as a flexible array. (Photo: Christian Wittek/IMPT)
  • Preliminary demonstrator: AMR sensors on a glass substrate chip, on top: a magnetic elastomer. (Photo: Maren Prediger/IMPT)
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