Resonance features of slender mechanical parts of Lorentz force MEMS magnetometers are affected by the (weakly) coupled thermo-electro-magneto-mechanical multi-physics governing their dynamics. We recently showed that reduced-order models for such parts can be written in the form of the Duffing equation, whose nonlinear term stems from the mechanical constraint on the vibrations and is affected by the driving voltage. As some device performance indices vary proportionally to the amplitude of oscillations at resonance, an optimization of the operational conditions may lead to extremely slender, imperfection-sensitive movable structures. In this work, we investigate the effects of imperfections on the mechanical response of a single-axis magnetometer. At the microscopic length-scale, imperfections are given in terms of uncertainties in the values of the over-etch depth and of the Young’s modulus of the vibrating polycrystalline silicon film. Their effects on the nonlinear structural dynamics are investigated through a Monte Carlo analysis, to show how the output of real devices can be scattered around the reference response trend.
HIS PAPER gives a complete description of the work briefly presented in [1]. Consumer products have recently started incorporating micro-magnetometers to be used as compasses. In combination with pressure sensors, accelerometers and gyroscopes, these sensors allow improved navigation both in scenarios where GPS is available and when it is not, such as for indoor navigation. In some cases this trend has already suggested the commercialization of multi-axis (or combo) MEMS sensor units.Lorentz force MEMS magnetometers [2]-[9] can be particularly advantageous with respect to other devices for the measurement of magnetic fields in the direction orthogonal to the substrate (z-axis magnetometers). When compared to Hall-effect sensors, Lorentz force devices have the advantage of lower power consumption and easier integration with standard, silicon-based, MEMS fabrication technologies.
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