A new low consumption 3D compass using integrated magnets and piezoresistive nano-gauges

Ettelt, Dirk; Rey, Patrice; Savoye, M.; Coutier, C.; Cartier, M.; Redon, O.; Audoin, M.; Walther, Arnaud; Robert, P.; Zhang, Y.; Dumas-Bouchiat, Frédéric; Dempsey, Nora; Delamare, Jérôme

doi:10.1109/transducers.2011.5969128

Cited by 8 publications

(5 citation statements)

References 7 publications

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“…A key challenge in magnetic MEMS is the realization of large-volume, high-energy-product permanent micromagnets that can be deposited in a fully-integrated and CMOS-compatible manner. Such magnets are essential in applications ranging from biasing of magnetic sensors in a portable compass [1] to high force MEMS magnetic actuators [2] to energy harvesting [3]. As an example, the generation of voltage in a permanent magnet energy harvester depends on the rate of change of flux (rather than flux density) according to Faraday's law of induction [4].…”

Section: Introductionmentioning

confidence: 99%

Retaining High Areal in-Plane Magnetic Energy Density Over Large Magnetic Thickness: a Permanent Magnetic Microlamination Approach Based on Sequential Multilayer Electroplating

Li¹,

Kim²,

Kim³

et al. 2014

2014 Solid-State, Actuators, and Microsystems Workshop Technical Digest

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Many magnetic MEMS devices such as magnetic-based microscale energy harvesters rely on the availability of microscale permanent magnets capable of generating significant magnetic fluxes. Ideally, these magnets would be able to be integrated with MEMS in a batch-fabrication-compatible manner. A number of thin film permanent magnets possessing excellent intrinsic magnetic properties have been discussed in the literature. In order to achieve higher extrinsic properties such as magnetic flux, an intuitive approach is to simply increase the magnetic film thickness. However, it is observed that as the magnetic film thickness increases, the intrinsic magnetic properties (such as remanence and maximum energy product) often deteriorate, limiting the maximum achievable magnetic fluxes from these small-scale integrated magnets. In this work, we present a microfabricated permanent magnet with a multilayer structure that preserves the high magnetic energy density (and resultant magnetic flux density) of thinner magnetic films while simultaneously achieving a significant magnetic thickness and resultant extrinsic properties. The fabrication process relies on sequential multilayer electroplating: alternating layers of relatively thin (in microns) magnetic films and non-magnetic materials were electrodeposited in a multilayer fashion realizing a laminated permanent micromagnet up to a total magnetic thickness of 80µm. A maximum energy product as high as 16.2kJ/m 3 (~ 70% of the value of a 1-µm-thick thin film) was retained in the laminated permanent micromagnet, and a 30% improvement over a CoNiP nonlaminated film with the same magnetic thickness has been successfully achieved. This fabrication approach could potentially be adapted to other permanent magnet materials systems.

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Section: Introductionmentioning

confidence: 99%

Retaining High Areal in-Plane Magnetic Energy Density Over Large Magnetic Thickness: a Permanent Magnetic Microlamination Approach Based on Sequential Multilayer Electroplating

Li¹,

Kim²,

Kim³

et al. 2014

2014 Solid-State, Actuators, and Microsystems Workshop Technical Digest

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“…The achieved performance well compares against state-of-the-art consumer devices. Ongoing work is dedicated to the development of the drive and sense low-power integrated circuitry, as well as to the cointegration of the described 3-axis gyroscope with accelerometers [5] and magnetometers [13], to form 9axis inertial measurement units. …”

Section: Discussionmentioning

confidence: 99%

Large full scale, linearity and cross-axis rejection in low-power 3-axis gyroscopes based on nanoscale piezoresistors

Dellea

Giacci

Longoni

et al. 2015

2015 28th IEEE International Conference on Micro Electro Mechanical Systems (MEMS)

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This work presents in-plane and out-of-plane Coriolis rate gyroscopes based on nano-scale piezoresistive readout and using an eutectic bonding between the bottom wafer, where the sensor is formed, and the cap wafer, where routing and metal pads are fabricated. The gyroscopes feature a novel design with a central levered sense frame, to maximize the device symmetry and compactness. The position of the piezoresistive nanogauges along the lever system optimizes the scale-factor. Operation on a ± 3000 dps full-scale-range (FSR) demonstrates quite competitive performance, with a linearity error lower than 0.25% and a cross-axis rejection 50x better than state-of-the art consumer gyroscopes.

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“…This M&NEMS concept of gyrometer enables the realization of extremely compact single-chip 3D gyroscopes while maintaining high performances: for consumer or automotive applications a size of the mechanical part of 0.5mm²/axis can be obtained while standard gyroscope sizes are higher than 1-2mm²/axis. The same concept has been recently adapted to a 3-axis magnetometer [5], therefore paving the way to the realization of an integrated and miniaturized 9 DOFs sensor.…”

Section: Nano Size Detection For Physical Sensorsmentioning

confidence: 99%

Nano Electro Mechanical Devices for Physical and Chemical Sensing

Polizzi

Duraffourg

Ollier³

et al. 2012

ECS Trans.

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The emergence of MEMS in consumer applications has dramatically increased market perspectives but also puts very strong constraints on cost and integration issues. Addressing these issues through further size reduction is not always relevant as it does not allow maintaining a correct signal to noise ratio (SNR) for the ubiquitous capacitive MEMS sensors. Different solutions are presented here according to the nature of the signal to be sensed: For physical sensors a new concept mixing a micron sized proof mass and a nano-sized detection structure is described. For chemical sensors, the reduction in size actually presents some advantages in terms of high resonant frequency, reduced gas damping, and high sensitivity to applied forces or added mass. Application of nano-resonators to gaz sensing is depicted.Developed originally at the end of the 80's, Micro Electro Mechanical Systems (MEMS) have by now given rise to a mature industry generating this year almost a 10 billion US$ turnover: Silicon micromachining techniques made possible the realisation of ultra-miniature and low cost sensors that allowed the deployment of airbags in cars (MEMS accelerometers are used there to measure the deceleration related to an accident), and more recently, new functions in smart phones.This deployment in large volume applications has triggered interest from large semiconductor industries (STM, TI, Freescale…) and a strong competition towards lower cost and higher integration: The new Grail of the industry is the realization of a 9 Degrees of Freedom sensor, combining the measurement in the 3 directions of space of acceleration, rotation speed and earth magnetic field.As inspired by the semiconductor industry, an obvious answer to these needs is to further decrease the size of the sensors, from Micro to Nano Electro Mechanical Systems (NEMS). However, even taking apart the technological challenges, this is not that simple as physics laws are not always in favour of scaling down: A simple homothetic size reduction does not allow maintaining a correct signal to noise ratio (SNR). As it will be seen here, different types of sensors require different approaches. Nano size detection for physical sensors.As mentioned before, inertial sensors are becoming one of the most ubiquitous sensor today, with applications in industrial, automotive or consumer applications. Further miniaturization is highly sought, as it allows both to decrease the cost (proportional to the surface of silicon) and increase integration (mandatory in portable applications such as smartphones, tablets…). However simple reduction of the seismic mass affects the sensitivity and reduces the nominal capacitance (95% of commercial MEMS

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A new low consumption 3D compass using integrated magnets and piezoresistive nano-gauges

Cited by 8 publications

References 7 publications

Retaining High Areal in-Plane Magnetic Energy Density Over Large Magnetic Thickness: a Permanent Magnetic Microlamination Approach Based on Sequential Multilayer Electroplating

Retaining High Areal in-Plane Magnetic Energy Density Over Large Magnetic Thickness: a Permanent Magnetic Microlamination Approach Based on Sequential Multilayer Electroplating

Large full scale, linearity and cross-axis rejection in low-power 3-axis gyroscopes based on nanoscale piezoresistors

Nano Electro Mechanical Devices for Physical and Chemical Sensing

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