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

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 MULTIPHYSICStrade 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.