Resonant Magnetic Field Sensor With Capacitive Driving and Electromagnetic Induction Sensing

This letter presents a novel magnetic field sensor, which consists of a square extensional mode resonator with a planar induction coil. This sensor exploits the principle of electromagnetic induction to detect external magnetic field through the electromotive force in the induction coil, which is placed on top of the resonant plate. The proposed sensor employs capacitive driving and electromagnetic induction sensing approach to detect the external magnetic field. The capacitive driving method reduces the power dissipation, and the electromagnetic induction sensing approach makes it easy to measure the output signal with high precision. The operation principle and fabrication process as well as the characterization of the magnetic field sensor are presented. Experimental result shows that the device offers a sensitivity of 3 μV/mT at its resonant frequency f₀ = 4.33 MHz in air. In this letter, the vibrating characterization of the sensor is largely reduced due to air damping. Therefore, vacuum packaging is needed to enhance the performance of the magnetic field sensor.