Geometric Optimization and Microstructuring of Magnetic Concentrators for a Resonant Magnetic Sensor

Abstract

This paper reports the design and analysis of a planar magnetic field concentrator with two gaps used for a resonant magnetic sensor and technology steps towards its realization. The device is based on a previously published resonant magnetic sensor combining a magnetic field concentrator and a mechanical resonator. A physical model is reported to explain the magnetic forces acting between the moveable inner part and the two fixed outer parts of the concentrator and the resulting magnetic field dependence of the resonance frequency. To optimize the concentrator and obtain highest sensitivity for the resonant sensor, three-dimensional magnetic finite element simulations using COMSOL MULTIPHYSICS ™ were performed. For the fabrication of planar concentrators made of amorphous soft magnetic material, ion beam etching (IBE), aqua regia wet etching and laser cutting were tested and evaluated.

Detecting the magnetic field direction by a cantilever operating in different vibration modes

“…Another approach reports a resonant magnetic microsensor sensitive enough to measure the earth magnetic field for compass applications [8,9,10]. The sensor combines an electrostatically driven micromechanical resonator and a planar magnetic concentrator with two narrow gaps [8,9,10].…”

Novel Fabrication Process for the Integration of MEMS Devices with Thick Amorphous Soft Magnetic Field Concentrators

“…The integration process combines silicon on insulator (SOI) technology for the MEMS device fabrication and epoxyresin-based attachment of amorphous soft magnetic ribbons followed by a wet chemical structuring process. The structure combines an electrostatically driven micromechanical resonator and an optimized planar magnetic field concentrator with two narrow gaps experiencing a resonance frequency shift in the presence of a magnetic field [9]. The sensor principle is shown in Figure 1.…”