In-Plane-Sense Magnetometer Based on Torsional MEMS With Vertically-Interlaced Combs via Self-Alignment Technique

We present a MEMS magnetometer based on the Faraday electromagnetic induction principle that works in the torsional resonance mode to sense in-plane magnetic fields. As for the device design and fabrication, a self-alignment technique is introduced to realize vertically-interlaced combs used for electrostatic driving for a torsional frame structure. In order to directly acquire relatively pure resonance characteristics of devices, an electromagnetic detection means with differential outputs is proposed to suppress the parasitic feed-through effect existing in the normal electrostatic-detection. Based on magnetic response tests, the proposed device has the measured sensitivity of 491 mV/mT with the non-linearity of 0.40% and the resolution of 6 μT under atmospheric pressure. Featured with the quasi-zero power consumption (75 nW), the measurement bandwidth without mechanical bandwidth limits, and the wide dynamic range (98 dB), this in-plane-sense device constituting as an essential for a 3-axis MEMS magnetometer has wide application prospects in automotive and portable electronics.