$Z$-Axis Magnetometers for MEMS Inertial Measurement Units Using an Industrial Process

Langfelder, Giacomo; Buffa, Cesare; Frangi, Attilio; Tocchio, Alessandro; Lasalandra, E.; Longoni, A.

doi:10.1109/tie.2012.2210958

Cited by 70 publications

(38 citation statements)

References 23 publications

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“…Though some works propose the integration of magnetic thin layers on top of suspended MEMS structures [2], most of the literature about MEMS magnetometers rely on the Lorentz force principle, as this concept allows avoiding magnetic materials and the corresponding need 10 for relatively low temperature during the fabrication steps (some magnetic materials begin losing their properties above about 300 ). Early works [3] and several thereafter [4,5,6] mostly focused on Lorentz-force devices to measure out-of-plane magnetic fields. Few examples of in-plane (either differential or non-differential) MEMS magnetometers were also described in the literature 15 [7,8,9,10,11,12,13].…”

Section: Introductionmentioning

confidence: 99%

Torsional MEMS magnetometer operated off-resonance for in-plane magnetic field detection

Laghi

Dellea

Longoni

et al. 2015

Sensors and Actuators A: Physical

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The work presents a microelectromechanical system (MEMS) based magnetometer, targeting compass applications performance, which measures magnetic fields along an in-plane direction. The magnetometer is fabricated with the surface micromachining process used for consumer gyroscopes, accelerometers, and recently proposed out-of-plane magnetometers. The magnetometer is based on the Lorentz force principle, so to avoid the need for magnetic materials integration. It features an area of 282 x 1095 µm 2 , and it is wafer-wafer packaged at a nominal pressure (0.35 mbar) similar to the one used for gyroscopes. In agreement with theoretical predictions, operation is demonstrated both at-resonance and off-resonance: in both situations the measured resolution, normalized to unit bandwidth and applied Lorentz current, is about 120 nT·mA/ √ Hz, but the maximum sensing bandwidth is extended from 4 Hz (at resonance) to 42Hz in off-resonance mode, which copes with consumer specifications. Within magnetic fields of ±5 mT, the device shows measured linearity errors <0.5% of the full-scale-range (demonstrating a large linearity) and a cross-axis rejection of ∼50 dB. The bias stability in off-resonance operation mode (80 nT·mA at 100 s) improves by a factor 100 with respect to resonance operation.

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Section: Introductionmentioning

confidence: 99%

Torsional MEMS magnetometer operated off-resonance for in-plane magnetic field detection

Laghi

Dellea

Longoni

et al. 2015

Sensors and Actuators A: Physical

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show abstract

“…The considerable improvements in the overall sensitivity predicted by simulations based on the rarefied gas theory are demonstrated by experimental results: in a representative example, the beams are driven by an AC current at resonance and used as Lorentz-force-based magnetometers [4]. It is experimentally demonstrated that, in this condition, one proposed structure shows an overall sensitivity which is 3× better than what obtained on devices based on continuous parallel plate stators and packaged in the same pressure conditions [6].…”

Section: Introductionmentioning

confidence: 85%

“…Standard parallel plate designs have an intrinsic limitation in that an increase in the sensing area (by using longer stators or several sensing cells in parallel) does not lead to any increase in the value of the sensitivity, when operating at resonance [6]. Indeed, since typical MEMS air gaps are few micrometers wide and typical pressures are in the order of 10 −3 bar, the free molecule flow regime applies and squeeze film damping dominates [7].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Sensing Stators in Capacitive MEMS Operating at Resonance

Frangi

Laghi

Langfelder

et al. 2015

J. Microelectromech. Syst.

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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-µm-thick surface micromachining process, demonstrate a 3× sensitivity improvement when used as resonant MEMS magnetometers.[ 2014-0297]Index Terms-Damping coefficient, quality factor, MEMS sensors, capacitive readout. 1057-7157

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“…This sensor has a sensitivity of 3 mV·T − 1 and a large output voltage offset (~1.9 mV). Langfelder et al [15] fabricated a magnetic field sensor formed by capacitive polysilicon plates with high aspect ratio that can have potential applications in inertial measurement units (IMUs). It has a compact structure with a sensitivity of 150 V⋅T -1 at 250 μA of peak driving current.…”

Section: Introductionmentioning

confidence: 99%

A MEMS-based magnetic field sensor with simple resonant structure and linear electrical response

Herrera-May

Lara-Castro

López-Huerta

et al. 2015

Microelectronic Engineering

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$Z$-Axis Magnetometers for MEMS Inertial Measurement Units Using an Industrial Process

Cited by 70 publications

References 23 publications

Torsional MEMS magnetometer operated off-resonance for in-plane magnetic field detection

Torsional MEMS magnetometer operated off-resonance for in-plane magnetic field detection

Optimization of Sensing Stators in Capacitive MEMS Operating at Resonance

A MEMS-based magnetic field sensor with simple resonant structure and linear electrical response

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