A Tunable MEMS Magnetic Sensor

This paper introduces a tunable MEMS magnetic field sensor. It uses torsional vibrations excited by Lorentz force to measure the strength of external magnetic fields. The sensor sensitivity and dynamic range can be tuned on-the-fly by varying its dc bias. Experimental demonstration shows that the sensor sensitivity can be tuned in the range of 0.139-0.283V/mT as the bias voltage varies from 0 to 6V in air and in the range of 0.038-0.955V/mT as the bias voltage varies from 0 to 5V in vacuum. While the sensor can operate in either a forced or a resonant mode, it achieves higher sensitivity and bandwidth when operating near its first torsional resonance.