A Resonant Lorentz-Force Magnetometer Based On Cavity Slotted Double-Ended Tuning Fork to Enhance Q-Factor and Sensitivity

Abstract

MEMS magnetometers have been applied in numerous fields, such as navigation, biomedical, geological exploration and aerospace. This work reports a resonant Lorentz-force magnetometer with a quality factor of 43000 in vacuum and a sensitivity of 3.3 Hz/nN under a 2 mT bias magnetic field. A differential pair of two magnetometers based on double-ended tuning fork (DETF) resonator is implemented to enhance the system signal to noise ratio (SNR). The topology of the DETF with cavity slots can improve the quality factor (Q-factor) effectively, resulting in an enhancement of 5.9-fold compared to a DETF resonator without slots. Theoretical computations are in good agreement with the simulation model and the actual experimental measurements confirm the feasibility of the proposed magnetometer. Future effort of this work will constitute an important step towards a magnetometer that can measure small variations of the magnetic field in tens of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{T}$</tex> range with a resolution of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{nT}/\surd\text{Hz}$</tex> level, even under a strong bias magnetic field.