Hybrid Magnetorheological Composites for Electric and Magnetic Field Sensors and Transducers

We present a simple, low-cost, and environmental-friendly method for the fabrication of hybrid magnetorheological composites (hMCs) based on cotton fibers soaked with a mixture of silicone oil (SO), carbonyl iron (CI) microparticles, and iron oxide microfibers (μF). The obtained hMCs, with various ratios (Φ) of SO and μF, are used as dielectric materials for manufacturing electrical devices. The equivalent electrical capacitance and resistance are investigated in the presence of an external magnetic field, with flux density B. Based on the recorded data, we obtain the variation of the relative dielectric constant (ϵr′), and electrical conductivity (σ), with Φ, and B. We show that, by increasing Φ, the distance between CI magnetic dipoles increases, and this leads to significant changes in the behaviour of ϵr′ and σ in a magnetic field. The results are explained by developing a theoretical model that is based on the dipolar approximation. They indicate that the obtained hMCs can be used in the fabrication of magneto-active fibers for fabrication of electric/magnetic field sensors and transducers.

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Graphene Platelets-Based Magnetoactive Materials with Tunable Magnetoelectric and Magnetodielectric Properties

Nanomaterials ◽

10.3390/nano10091783 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1783

Author(s):

Ioan Bica ◽

Eugen Mircea Anitas

Keyword(s):

Magnetic Field ◽

Silicone Oil ◽

Dielectric Materials ◽

Cotton Fibers ◽

Magnetic Flux Density ◽

Electrical Capacitance ◽

Medium Frequency ◽

Physical Mechanisms ◽

Electrical Devices ◽

Living Organisms

We fabricate hybrid magnetoactive materials (hMAMs) based on cotton fibers, silicone oil, carbonyl iron and graphene nanoplatelets (nGr) at various mass concentrations ΦnGr. The obtained materials are used as dielectric materials for manufacturing plane electrical capacitors. The equivalent electrical capacitance Cp and resistance Rp are measured in an electric field of medium frequency f, without and respectively with a magnetic field of magnetic flux density B in the range from 0.1 T up to 0.5 T. The results are used to extract the components ϵr′ and ϵr″ of the complex relative permittivity ϵr*, and to reveal the magnitude of the induced magnetoelectric couplings kx and magnetodielectric effects MDE. It is shown that ϵr′, ϵr″, kx and MDE are significantly influenced by f,B and ΦnGr. We describe the underlying physical mechanisms in the framework of dipolar approximation and using elements of dielectric theory. The tunable magnetoelectric and magnetodielectric properties of hMAMs are useful for manufacturing electrical devices for electromagnetic shielding of living organisms.

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Electrical and Magnetodielectric Properties of Magneto-Active Fabrics for Electromagnetic Shielding and Health Monitoring

International Journal of Molecular Sciences ◽

10.3390/ijms21134785 ◽

2020 ◽

Vol 21 (13) ◽

pp. 4785

Author(s):

Madalin Bunoiu ◽

Eugen Mircea Anitas ◽

Gabriel Pascu ◽

Larisa Marina Elisabeth Chirigiu ◽

Ioan Bica

Keyword(s):

Electrical Properties ◽

Electric Fields ◽

Health Monitoring ◽

Silicone Oil ◽

Low Cost ◽

Relaxation Times ◽

Dielectric Materials ◽

Medium Frequency ◽

Mass Fractions ◽

Electromagnetic Pollution

An efficient, low-cost and environmental-friendly method to fabricate magneto-active fabrics (MAFs) based on cotton fibers soaked with silicone oil and iron oxide microfibers (mFe) at mass fractions 2 wt.%, 4 wt.% and 8 wt.% is presented. It is shown that mFe induce good magnetic properties in MAFs, which are subsequently used as dielectric materials for capacitor fabrication. The electrical properties of MAFs are investigated in a static magnetic field with intensities of 0 kA/m, 160 kA/m and 320 kA/m, superimposed on a medium-frequency electric field. The influence of mFe on the electrical capacitance and dielectric loss tangent is determined, and it can be observed that the electrical conductivity, dielectric relaxation times and magnetodielectric effects are sensibly influenced by the applied magnetic and electric fields. The results indicate that the MAFs have electrical properties which could be useful for protection against electromagnetic pollution or for health monitoring.

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Fast AHRS Filter for Accelerometer, Magnetometer, and Gyroscope Combination with Separated Sensor Corrections

Sensors ◽

10.3390/s20143824 ◽

2020 ◽

Vol 20 (14) ◽

pp. 3824 ◽

Cited By ~ 2

Author(s):

Josef Justa ◽

Václav Šmídl ◽

Aleš Hamáček

Keyword(s):

Microelectromechanical Systems ◽

Low Cost ◽

Computational Cost ◽

Ground Truth ◽

Fast Evaluation ◽

Magnetic Field Sensors ◽

Source Codes ◽

Recorded Data ◽

Using Data ◽

Predictor Corrector

A new predictor–corrector filter for attitude and heading reference systems (AHRS) using data from an orthogonal sensor combination of three accelerometers, three magnetometers and three gyroscopes is proposed. The filter uses the predictor—corrector structure, with prediction based on gyroscopes and independent correction steps for acceleration and magnetic field sensors. We propose two variants of the filter: (i) one using mathematical operations of special orthogonal group SO(3), that are accurate for nonlinear operations, for highest possible accuracy, and (ii) one using linearization of nonlinear operations for fast evaluation. Both approaches are quaternion-based filter realizations without redundant steps. The filters are compared to state of the art methods in this field on data recorded using low-cost microelectromechanical systems (MEMS) sensors with ground truth measured by the VICON optical system. Both filters achieved better accuracy than conventional methods at lower computational cost. The recorded data with ground truth reference and the source codes of both filters are publicly available.

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Physical Mechanisms of Magnetic Field Effects on the Dielectric Function of Hybrid Magnetorheological Suspensions

Materials ◽

10.3390/ma14216498 ◽

2021 ◽

Vol 14 (21) ◽

pp. 6498

Author(s):

Gabriela-Eugenia Iacobescu ◽

Ioan Bica ◽

Larisa-Marina-Elisabeth Chirigiu

Keyword(s):

Magnetic Field ◽

Silicone Oil ◽

Dipole Approximation ◽

Time Interval ◽

Magnetic Field Effects ◽

Three Solutions ◽

Magnetic Dipoles ◽

Physical Mechanisms ◽

Electric Capacitance ◽

Magnetorheological Suspensions

In this paper, we study the electrical properties of new hybrid magnetorheological suspensions (hMRSs) and propose a theoretical model to explain the dependence of the electric capacitance on the iron volumetric fraction, ΦFe, of the dopants and on the external magnetic field. The hMRSs, with dimensions of 30 mm×30 mm×2 mm, were manufactured based on impregnating cotton fabric, during heating, with three solutions of iron microparticles in silicone oil. Flat capacitors based on these hMRSs were then produced. The time variation of the electric capacitance of the capacitors was measured in the presence and absence of a magnetic field, B, in a time interval of 300 s, with Δt=1 s steps. It was shown that for specific values of ΦFe and B, the coupling coefficient between the cotton fibers and the magnetic dipoles had values corresponding to very stable electrical capacitance. Using magnetic dipole approximation, the mechanisms underlying the observed phenomena can be described if the hMRSs are considered continuous media.

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The Study of a MEMS Magnetic Field Sensor Based on “Cross-Shape” Ferromagnetic Film

Materials Science Forum ◽

10.4028/www.scientific.net/msf.694.523 ◽

2011 ◽

Vol 694 ◽

pp. 523-527 ◽

Cited By ~ 1

Author(s):

Qi Bin Lin ◽

Guang Tao Du

Keyword(s):

Magnetic Field ◽

Low Cost ◽

Ferromagnetic Film ◽

Wheatstone Bridge ◽

Diaphragm Thickness ◽

Magnetic Field Sensors ◽

Sensor Performance ◽

Element Simulation ◽

Field Sensor ◽

The Magnetic Field

Novel magnetic field sensors are based on a “cross-shape” ferromagnetic film (FMF) attached to a silicon diaphragm and piezoresistive membrane. The interaction between the magnetic field and the (FMF) generates a deflection of the diaphragm, which changes the piezoresistance and unbalances a Wheatstone bridge. The effect of FMF and silicon diaphragm thickness on the sensor performance is studied by the finite element simulation. The performance of sensor can be improved by optimizing the size of “cross-shape” FMF. These low-cost, low-power sensors are easily integrated with electronic circuits.

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