A Horseshoe Micromachined Resonant Magnetic Field Sensor With High Quality Factor

We report a magnetic field sensor shaped in the form of a horseshoe silicon micromechanical resonator. Through coupling a pair of resonating tines on one end, we are able to achieve a Q of 14 400. This benefits the field sensitivity of the device, which has a linear dependence on the mechanical displacement of the tines that is caused by a Lorentz force. The strength of the magnetic field density is thus inferred from the mechanical displacement. The device has a measured sensitivity of 4.6 mm/(A·T), which agrees well with the proposed analytical model. By scaling the dimensions of the device to a lateral size similar to that of other referenced works based on similar principles, the model predicts a tenfold improvement in sensitivity in comparison. The enhancement is due to the higher Q, achieved by merit of the novel device topology.