Monolithic 3-Axis MEMS Multi-Loop Magnetometer: A Performance Analysis

Abstract

The work introduces the first MEMS Lorentz-force magnetometer that both includes multiple current recirculation loops and combines in a single, low-footprint (<;0.5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), monolithic device the sensitivity along three spatial directions. This is obtained through an innovative electromechanical design based on: 1) two torsional nested modes to sense in-plane fields; 2) a nested antiphase in-plane mode to sense out-of-plane fields; and 3) aluminum path to define the recirculating loop trajectory. Operated off-resonance with a 200-μArms sinewave current delivered from an MEMS-based oscillator, the sensor reaches on all axes noise levels of 100 nT/√Hz over a 50-Hz 3-dB bandwidth, with a full-scale range of ±7 mT and 0.1% nonlinearity. Cross-axis contributions, inherently higher than in separate-axis sensors, are linearly compensated to less than 1.5%.