Novel teeter-totter 2-axes MEMS magnetometer with equal sensitivities

Abstract

In this paper, we demonstrate a novel 2-axes MEMS-based resonant magnetic field sensor. It is a compact magnetometer, build in a single MEMS layer, which measures the two in-plane components of magnetic field and this with equal relative sensitivity. Its principle of operation is based on Lorentz force acting on a current carrying conductor placed in a magnetic field B. The force is proportional to the magnetic field B and for this particular design it results in a torque exerted on the microstructure, resulting a rotation (teeter-tooter) motion of the structure, which on its turns is translated into a differential capacitance. The proposed magnetometer design fits a chip area less than 250[μm]×300[μm]. An analytical design approach is described to reach to the equal and maximal relative sensitivity. Using FEM simulations, A relative sensitivity 3547[T-1] was reached. The design makes that cross sensitivities between the 2-axes is as small as possible. Also, for the first time, we introduce an equivalent circuit of a torsional MEMS magnetometer. It was developed starting from the known transducers like electrodynamic and electrostatic transducers.