scholarly journals The Performance of the Magneto-Impedance Effect for the Detection of Superparamagnetic Particles

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1961 ◽  
Author(s):  
Alfredo García-Arribas
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
External Field ◽  
Stray Magnetic Field ◽  
Superparamagnetic Particles ◽  
Impedance Response ◽  
Finite Element Calculations ◽  
Impedance Sensor

The performance of magneto-impedance sensors to detect the presence and concentration of magnetic nanoparticles is investigated, using finite element calculations to directly solve Maxwell’s equations. In the case of superparamagnetic particles that are not sufficiently magnetized by an external field, it is assumed that the sensitivity of the magneto-impedance sensor to the presence of magnetic nanoparticles comes from the influence of their magnetic permeability on the sensor impedance, and not from the stray magnetic field that the particles produce. The results obtained not only justify this hypothesis, but also provide an explanation for the discrepancies found in the literature about the response of magneto-impedance sensors to the presence of magnetic nanoparticles, where some authors report an increasing magneto-impedance signal when the concentration of magnetic nanoparticles is increased, while others report a decreasing tendency. Additionally, it is demonstrated that sensors with lower magneto-impedance response display larger sensitivities to the presence of magnetic nanoparticles, indicating that the use of plain, nonmagnetic conductors as sensing materials can be beneficial, at least in the case of superparamagnetic particles insufficiently magnetized in an external magnetic field.

scholarly journals Отклик решетки магнитных наночастиц на импульс магнитного поля вблизи границы устойчивости

2018 ◽  
Vol 60 (1) ◽  
pp. 94
Author(s):  
А.М. Шутый ◽  
Д.И. Семенцов
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
External Field ◽  
Stable Equilibrium ◽  
Initial Conditions ◽  
Entire System ◽  
Magnetic Field Pulse ◽  
Field Pulse ◽  
Crystallographic Anisotropy

AbstractThe dynamic response of a system being near the stable equilibrium boundary to an external magnetic field pulse is studied for 2D lattices of magnetic nanoparticles with cubic crystallographic anisotropy. The conditions under which magnetic moment oscillations from individual dipoles propagate to the entire system are revealed. This effect results in the lattice response are significantly larger in the external pulse duration and with an amplitude rather weakly depending on initial conditions and external field parameters, the processes during which the pulse results in reorientation of only individual lattice dipoles.

scholarly journals Magnetoviscosity of a Magnetic Fluid Based on Barium Hexaferrite Nanoplates

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1870
Author(s):  
Dmitry Borin ◽  
Robert Müller ◽  
Stefan Odenbach
Keyword(s):  
Magnetic Field ◽  
Experimental Study ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
Shear Flow ◽  
Magnetic Fluid ◽  
Barium Hexaferrite ◽  
Dipole Interaction ◽  
Field Dependent ◽  
Fluid Behaviour

This paper presents the results of an experimental study of the influence of an external magnetic field on the shear flow behaviour of a magnetic fluid based on barium hexaferrite nanoplates. With the use of rheometry, the magnetoviscosity and field-dependent yield-stress in the fluid are evaluated. The observed fluid behaviour is compared to that of ferrofluids with magnetic nanoparticles having high dipole interaction. The results obtained supplement the so-far poorly studied topic of the influence of magnetic nanoparticles’ shape on magnetoviscous effects. It is concluded that the parameter determining the observed magnetoviscous effects in the fluid under study is the ratio V2/l3, where V is the volume of the nanoparticle and l is the size of the nanoparticle in the direction corresponding to its orientation in the externally applied magnetic field.

Mittag–Leffler Function as an Approximant to the Concentrated Ferrofluid’s Magnetization Curve

2021 ◽  
Vol 5 (4) ◽  
pp. 147
Author(s):  
Petr A. Ryapolov ◽  
Eugene B. Postnikov
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
Magnetization Curve ◽  
Force Fields ◽  
Physical Characteristics ◽  
Concentrated Solutions ◽  
Static Magnetization ◽  
Simple Tool ◽  
Technical Systems

In this work, we show that the static magnetization curve of high-concentrated ferrofluids can be accurately approximated by the Mittag–Leffler function of the inverse external magnetic field. The dependence of the Mittag–Leffler function’s fractional index on physical characteristics of samples is analysed and its growth with the growing degree of system’s dilution is revealed. These results provide a certain background for revealing mechanisms of hindered fluctuations in concentrated solutions of strongly interacting of the magnetic nanoparticles as well as a simple tool for an explicit specification of macroscopic force fields in ferrofluid-based technical systems.

Infinite solitons in ferromagnetic materials with an internal magnetic field

2021 ◽  
pp. 2150413
Author(s):  
Hamdy I. Abdel-Gawad
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
External Field ◽  
Model Equation ◽  
Graphical Representation ◽  
Magnetic Moments ◽  
Soliton Solutions ◽  
Internal Magnetic Field ◽  
Multiple Soliton Solutions ◽  
The Magnetic Field

The ferromagnetism induced by an external magnetic field (EMF), in (3+1) dimensions, is governed by Kraenkel–Manna–Merle system (KMMS). A (1+1) dimension model equation was derived in the literature. The magnetic moments are parallel to the magnetic field in ferromagnetism as they are aligning in the same direction of the external field. Here, it is shown that the KMMS supports the presence of internal magnetic field. This may be argued to medium characteristics. The objective of this work is to mind multiple soliton solutions, which are obtained via the generalized together with extended unified methods. Graphical representation of the results are carried. They describe infinite soliton shapes, which arise from the multiple variation of the arbitrary functions in the solutions. It is, also, shown that internal magnetic field decays, asymptotically, to zero with time.

scholarly journals Simultaneous polydirectional transport of colloidal bipeds

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Mahla Mirzaee-Kakhki ◽  
Adrian Ernst ◽  
Daniel de las Heras ◽  
Maciej Urbaniak ◽  
Feliks Stobiecki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
External Field ◽  
Colloidal Particles ◽  
Addition Reaction ◽  
Lab On A Chip ◽  
Magnetic Pattern ◽  
Colloidal Spheres ◽  
Colloidal Science ◽  
Colloidal Rods

Abstract Detailed control over the motion of colloidal particles is relevant in many applications in colloidal science such as lab-on-a-chip devices. Here, we use an external magnetic field to assemble paramagnetic colloidal spheres into colloidal rods of several lengths. The rods reside above a square magnetic pattern and are transported via modulation of the direction of the external magnetic field. The rods behave like bipeds walking above the pattern. Depending on their length, the bipeds perform topologically distinct classes of protected walks. We design parallel polydirectional modulation loops of the external field that command up to six classes of bipeds to walk on distinct predesigned paths. Using such loops, we induce the collision of reactant bipeds, their polymerization addition reaction to larger bipeds, the separation of product bipeds from the educts, the sorting of different product bipeds, and also the parallel writing of a word consisting of several letters. Our ideas and methodology might be transferred to other systems for which topological protection is at work.

scholarly journals Synthesis of Poly-Sodium-Acrylate (PSA)-Coated Magnetic Nanoparticles for Use in Forward Osmosis Draw Solutions

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1238 ◽  
Author(s):  
Irena Ban ◽  
Sabina Markuš ◽  
Sašo Gyergyek ◽  
Miha Drofenik ◽  
Jasmina Korenak ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
Osmotic Pressure ◽  
Forward Osmosis ◽  
Superparamagnetic Nanoparticles ◽  
Molar Ratio ◽  
Sodium Acrylate ◽  
Molar Ratios ◽  
Magnetite Phase

The synthesis of magnetic nanoparticles (MNPs) coated with hydrophilic poly-sodium-acrylate (PSA) ligands was studied to assess PSA-MNP complexes as draw solution (DS) solutes in forward osmosis (FO). For MNP-based DS, the surface modification and the size of the MNPs are two crucial factors to achieve a high osmolality. Superparamagnetic nanoparticles (NP) with functional groups attached may represent the ideal DS where chemical modifications of the NPs can be used in optimizing the DS osmolality and the magnetic properties allows for efficient recovery (DS re-concentration) using an external magnetic field. In this study MNPs with diameters of 4 nm have been prepared by controlled chemical co-precipitation of magnetite phase from aqueous solutions containing suitable salts of Fe2+ and Fe3+ under inert atmosphere and a pure magnetite phase could be verified by X-ray diffraction. Magnetic colloid suspensions containing PSA-coated MNPs with three different molar ratios of PSA:MNP = 1:1, 1:2 and 1:3 were prepared and assessed in terms of osmotic pressure, aggregation propensity and magnetization. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of PSA on coated MNPs and pristine PSA-MNPs with a molar ratio PSA:MNP = 1:1 exhibited an osmotic pressure of 30 bar. Molar ratios of PSA:MNP = 1:2 and 1:3 lead to the formation of less stabile magnetic colloid solutions, which led to the formation of aggregates with larger average hydrodynamic sizes and modest osmotic pressures (5.5 bar and 0.2 bar, respectively). After purification with ultrafiltration, the 1:1 nanoparticles exhibited an osmotic pressure of 9 bar with no aggregation and a sufficient magnetization of 25 emu/g to allow for DS regeneration using an external magnetic field. However, it was observed that the amount of PSA molecules attached to the MNPs decreased during DS recycling steps, leaving only strong chelate-bonded core-shell PSA as coating on the MNPs. This demonstrates the crucial role of MNP coating robustness in designing an efficient MNP-based DS for FO.

Use of synthesized hydrophilic magnetic nanoparticles (HMNPs) in forward osmosis for water reuse

2015 ◽  
Vol 16 (1) ◽  
pp. 229-236 ◽  
Author(s):  
Tripti Mishra ◽  
Sudipta Ramola ◽  
Anil Kumar Shankhwar ◽  
R. K. Srivastava
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
Functional Groups ◽  
Water Reuse ◽  
Surface Composition ◽  
Forward Osmosis ◽  
Chemical Compositions ◽  
One Pot ◽  
Metal Precursor

Forward osmosis (FO) is attracting worldwide attention as an emerging technology in the fields of power generation, water reuse, desalination, pharmaceuticals and food processing. Still, the critical challenge of finding a suitable draw solute for FO persists. Therefore the current research focuses on synthesizing hydrophilic magnetic nanoparticles (HMNPs) and systematically investigating their potential as draw solutes. HMNPs were synthesized using functional groups polyethylene glycol (PEG 400) and polyacrylic acid (PAA). These functional groups under different ratios with a metal precursor react by one-pot polyol and thermal decomposition methods respectively to give different diameter HMNPs. In addition the effect of different sizes of synthesized HMNPs was investigated for their recovery under an external magnetic field and reusability in FO performance. The physical properties and chemical compositions of the resultant MNPs are fully characterized. Transmission electron microscopy (TEM) analyses show the characteristics as spherical morphology with a narrow size distribution, and a mean size from 9 to 32.5 nm for PEG and 8 to 30 nm for PAA coated HMNPs depending on the ratio of the functional group and metal precursor. The PEG and PAA layer on the MNPs is confirmed by Fourier transform infrared (FTIR) analysis, and thermogravimetric analysis demonstrates a hydrophilic surface composition. The PEG and PAA coated HMNPs generate high osmotic pressures and exhibit good dispersibility in aqueous solutions. Water fluxes of >13 L m−2 h−1 are achieved across Hydration Technologies Inc. flat sheet membranes at a concentration of 0.05 M of HMNPs using deionized water as the feed solution. The HMNPs can be easily recaptured from draw solutions by applying an external magnetic field and recycling them back as draw solute in the FO process. The MNPs remain active after nine runs of recycling but with a total water flux decrease of 5% in PEG and 3% with each successive recycling due to slight aggregation, and reduced surface to volume ratio is observed. Results of the present study have demonstrated that PEG and PAA coated HMNPs can viewed as promising and potential draw solutes in the FO process.

Dynamics of the magnetic nanoparticles lattice in an external magnetic field

2018 ◽  
Vol 464 ◽  
pp. 76-90 ◽  
Author(s):  
Anatolij M. Shuty ◽  
Svetlana V. Eliseeva ◽  
Dmitrij I. Sementsov
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field
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