A MEMS Resonant Lorentz-Force Magnetometer with Both Structural Topology Optimization and Parametric Pumping for Q-Factor Enhancement

This paper reports a miniaturized MEMS resonant magnetometer with higher Lorentz-force sensitivity and resolution compared to the state-of-the-art, and improved performance in contrast with previous work reported in [6]. The proposed device features a structural topology to minimize the thermoelastic dissipation, in particular, a double-ended tuning fork (DETF) resonator with cavity slots. An energy injection technique based on parametric pumping is employed to improve the Q-factor further. The device thus combines, for the first time, both active and passive approaches simultaneously to optimize the Q-factor of a microresonator, and ultimately, to attain a superior sensing performance for practical applications. The proposed magnetometer achieves a quality factor of 70120 in a rough vacuum of 1 Pa, which is 9.6-fold higher than that of a common DETF resonator with the same geometry. Experimental results confirm that the proposed magnetometer with the assistance of both active and passive methods to optimize the energy dissipation yields a Lorentz-force sensitivity of 0.55 Hz/nN and a resolution of 5.45 pN/√Hz, under a fixed magnetic field of 38 mT.