An Electromagnetic Induction Based Torsional MEMS Magnetometer for In-Plane Magnetic Field Sensing

In this paper, we show an electromagnetic induction based torsional MEMS magnetometer for in-plane magnetic field sensing. The magnetometer is constructed of a seesaw plate, two torsional beams, two equivalent parallel-plate driving electrodes and two layers aluminum induction coil. The seesaw plate is excited into the torsional resonance mode by electrostatic force. When the target magnetic field is applied to the magnetometer, the induction coil patterned on the seesaw cuts the magnetic induction line and an induced voltage appears across the output ports. We etched the damping holes in the seesaw to decrease the air damping to improve the sensitivity. The proposed magnetometer is fabricated by the standard SOG (Silicon-on-Glass) process. In air, the magnetometer registers high magnetic field sensitivity of 100 mV/mT, excellent linearity with non-linear error less than 0.3%, extremely low power consumption less than 1 μW, and high resolution of 25 μT, which makes it suitable for automotive industry, navigation systems and non-destructive material testing.