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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 mm2), 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- $\mu \text{A}_{\text {rms}}$ sinewave current delivered from an MEMS-based oscillator, the sensor reaches on all axes noise levels of 100 nT/ $\surd $ 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%. [2018-0056] [ABSTRACT FROM AUTHOR]

This paper validates an innovative simulation tool for the prediction of gas damping occurring in MEMS working in near vacuum at frequencies in the range of 20–30 kHz. Three different families of test devices, representing standard building blocks of MEMS, have been designed, fabricated, tested, and simulated. A total of 292 structures belonging to 36 different geometries have been addressed in order to confirm the ability of the numerical model to capture the dependence on geometrical parameters and to provide a quantitative prediction. Tests have been operated both at variable pressures in a vacuum chamber and in the closed package, and demonstrate an accuracy in the order of 15%. [2016-0060] [ABSTRACT FROM AUTHOR]

This paper presents the principle and complete characterization of a single-chip unit formed by microelectromechanical system magnetometers to sense the 3-D magnetic field vector and a Tang resonator. The three sensors, nominally with the same resonance frequency, are operated 200-Hz off-resonance through an ac current whose reference frequency is provided by the resonator embedded in an oscillating circuit. The sensors gain is increased by adopting a current recirculation strategy using metal strips directly deposited on the structural polysilicon. At a driving value of 100 \mu \textA\mathrm{ rms} flowing in series through the three devices, the magnetometers show a sub-185 nT/ $\vphantom {{\sqrt {\mathrm{ Hz}}}^{a}}\sqrt {\mathrm{ Hz}}$ resolution with a selectable bandwidth up to 50 Hz. Over a ±5-mT full-scale range, the sensitivity curves show linearity errors lower than 0.2%, with high cross-axis rejection and immunity to external accelerations. Under temperature changes, the stability of the 200-Hz difference between the magnetometers and the resonator frequency is within 55 ppm/K. Offset is trimmed down to the microtesla range, with an overall measured Allan stability of about 100 nT at 20-s observation time. [2016-0030] [ABSTRACT FROM PUBLISHER]

This paper presents a novel z -axis Lorentz force magnetometer coupled with a low-power readout integrated circuit. The sensor is fabricated using an industrial process, and exploits an Al-on-polysilicon multi-loop architecture that gives a five-fold sensitivity and resolution improvement, useful for off-resonance operation. The integrated readout is based on a differential charge amplifier front-end, and designed to be balanced with the sensor in terms of noise and power consumption. The overall system, including demodulation and filtering stages, shows a programmable full-scale up to ±2.4 mT, limited by the electronics saturation. The bandwidth can be programmed up to 150 Hz for off-resonance operation where a sub-400-nT/ \sqrt \text Hz resolution at 775- \mu \textW power consumption is obtained, including the integrated readout and the Lorentz current. Perspectives on low-consumption driving oscillators for off-resonance mode are finally given. [2015-0139] [ABSTRACT FROM AUTHOR]

This paper describes capacitive sensing stators for microelectromechanical systems (MEMS) suitably designed to minimize damping effects without worsening the capacitive variation per unit displacement. Such optimization can be exploited to maximize the readout signal in resonant systems. Two structures are designed with the aid of finite-element method models for the electrostatic domain, and with the aid of a deterministic integral model for damping predictions. The structures, fabricated in a 22- $\mu $ m-thick surface micromachining process, demonstrate a $3\times $ sensitivity improvement when used as resonant MEMS magnetometers. [ABSTRACT FROM PUBLISHER]

This paper demonstrates bandwidth extension for Lorentz force microelectromechanical systems magnetometers operated at a frequency slightly lower than the mechanical resonance. This off-resonance mode of operation also minimizes the critical tradeoff between maximum sensing bandwidth and minimum measurable field, enabling low-pressure operation and the associated resolution improvement. The experimental verification is obtained using two identical devices packaged at two different pressures and tested with a suitable low-noise board-level electronics. The first device, packaged at 1 mbar, has a (mechanical) sensing bandwidth of $\sim$50 Hz, and a resolution per unit bandwidth and driving current of 290 \nT\cdot\mA/\surd\Hz. With the second device, packaged at 0.25 mbar and operated off-resonance, roughly twice better resolution (160 \nT\cdot\mA/\surd\Hz) and four times larger bandwidth ( $>$200 Hz) are obtained. [ABSTRACT FROM PUBLISHER]