Magnetophoretic assembly of flexible nanoparticles/lipid microfilaments

2015 ◽  
Vol 181 ◽  
pp. 437-448 ◽  
Author(s):  
Bhuvnesh Bharti ◽  
Anne-Laure Fameau ◽  
Orlin D. Velev
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticle ◽  
Colloidal Particles ◽  
Practical Importance ◽  
Directed Assembly ◽  
Lipid Binding ◽  
Self Healing ◽  
New Class ◽  
Linear Chains ◽  
The Magnetic Field

The directed assembly of colloidal particles into linear chains and clusters is of fundamental and practical importance. In this study we characterize and analyse the mechanism of the magnetic field driven assembly of lipid-coated iron oxide nanoparticles into flexible microfilaments. Recently we showed that nanocapillary lipid binding can form a new class of magnetic nanoparticle-lipid microfilaments with unprecedented flexibility and self-healing properties. In the presence of a uniform magnetic field, the magnetophoretic attraction of the particles combined with interparticle dipole–dipole attraction drives the microfilament assembly. The fluid like lipid layer on the particles leads to stickiness on the surface of the filaments and the magnetic field concentration overcomes the potential electrostatic repulsion in the water phase. The lipid capillary bridges formed between the particles facilitate their permanent binding and sustain the flexible microfilament structure. We demonstrate that this surface stickiness combined with the magnetic response of the filaments can be used further to twist, bend and bundle the microfilaments into unusual structures.

BIREFRINGENCE AND MAGNETO-OPTICAL PROPERTIES IN OLEIC ACID COATED Fe3O4 NANOPARTICLES: APPLICATION FOR OPTICAL SWITCH

2011 ◽  
Vol 10 (03) ◽  
pp. 515-520 ◽  
Author(s):  
SI-HUA XIA ◽  
JUN WANG ◽  
ZHANG-XIAN LU ◽  
FEIYAN ZHANG
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Oleic Acid ◽  
Magnetic Nanoparticles ◽  
Magnetic Nanoparticle ◽  
Optical Switch ◽  
Colloidal Suspension ◽  
Experimental Parameters ◽  
Nanoparticle Chains ◽  
The Magnetic Field

We report magneto-optical properties in a kerosene colloidal suspension of oleic acid coated Fe3O4 nanoparticles (~14 nm). The magnetic colloids (fluids) show birefringence under a magnetic field. Systematical studies of the on–off switch times upon application of the on–off magnetic field with varied experimental parameters indicate that the switch response time depends strongly on the strength of the magnetic field and the concentration of the magnetic nanoparticles in the fluid. The data can be explained in terms of the formation of magnetic nanoparticle chains under a magnetic field. The important magneto-optical properties of the magnetic fluids allow us to design a tunable optical switch.

Characteristics of Ultrasound Propagation in a Magnetic Fluid Under Uniform Magnetic Field

2003 ◽  
Author(s):  
Masaaki Motozawa ◽  
Tatsuo Sawada
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fluid ◽  
Uniform Magnetic Field ◽  
Colloidal Particles ◽  
Magnetic Field Intensity ◽  
Magnetic Field Direction ◽  
Ultrasound Propagation ◽  
Ultrasonic Propagation ◽  
The Magnetic Field

When an external magnetic field is applied to a magnetic fluid, some of the colloidal particles coagulate and form chain-like clusters. Properties of ultrasonic propagation wave are changed by these chain-like clusters. We carried out measurement of the ultrasonic propagation velocity in a magnetic fluid. Measurement were made by changing the magnetic field intensity from 0 mT to 570 mT, and the angle between the magnetic field direction and direction of the ultrasound propagation from 0° to 180°. The ultrasound frequencies were 1 MHz, 2 MHz and 4 MHz. Some of experimental results for the characteristics of ultrasound propagation in a magnetic fluid under a uniform magnetic field were reported.

STRUCTURES IN A MAGNETIC SUSPENSION SUBJECTED TO UNIDIRECTIONAL AND ROTATING FIELD

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2279-2285 ◽  
Author(s):  
P. CARLETTO ◽  
G. BOSSIS ◽  
A. CEBERS
Keyword(s):  
Magnetic Field ◽  
Surface Tension ◽  
Thermodynamic Model ◽  
Colloidal Particles ◽  
Average Distance ◽  
Characteristic Size ◽  
Magnetic Suspension ◽  
Order Of Magnitude ◽  
The Magnetic Field ◽  
Rotating Field

Field induced structures are studied inside suspensions of magnetic colloidal particles of micronic size. We have characterized the average distance between aggregates in a thin cell with the magnetic field perpendicular to the plane and also in the presence of a rotating field with the plane of rotation perpendicular to the plane of the cell. The characteristic size of the mesostructure is predicted on the basis of a thermodynamic model. The theory well predicts the experimental results in the uniaxial case but not in the case of ae rotating field; in this last case, the surface tension which is needed to have a good fit is far too low compared to its expected order of magnitude. When the field is uniaxial and sinusoidal we have found a collective instability where all the aggregates are rotating simultaneously in a chaotic way.

A feasibility study of magnetic separation of magnetic nanoparticle for forward osmosis

2011 ◽  
Vol 64 (2) ◽  
pp. 469-476 ◽  
Author(s):  
Y. C. Kim ◽  
S. Han ◽  
S. Hong
Keyword(s):  
Magnetic Field ◽  
Magnetic Separation ◽  
High Performance ◽  
Magnetic Nanoparticle ◽  
Large Scale ◽  
Magnetic Field Gradient ◽  
Forward Osmosis ◽  
Magnetic Separator ◽  
High Gradient Magnetic Separation ◽  
The Magnetic Field

It was recently reported that a UK company has developed a naturally non-toxic magnetoferritin to act as a draw solute for drawing water in forward osmosis process. The gist of this technology is the utilization of the magnetic nanoparticle and high-gradient magnetic separation for draw solute separation and reuse. However, any demonstration on this technology has not been reported yet. In this study, a feasibility test of magnetic separation using magnetic nanoparticle was therefore performed to investigate the possibility of magnetic separation in water treatment such as desalination. Basically, a magnetic separation system consisted of a column packed with a bed of magnetically susceptible wools placed between the poles of electromagnet and Fe3O4 magnetic nanoparticle was used as a model nanoparticle. The effect of nanoparticle size to applied magnetic field in separation column was experimentally investigated and the magnetic field distribution in a magnet gap and the magnetic field gradient around stainless steel wool wire were analyzed through numerical simulation. The amount of magnetic nanoparticle captured in the separator column increased as the magnetic field strength and particle size increased. As a result, if magnetic separation is intended to be used for draw solute separation and reuse, both novel nanoparticle and large-scale high performance magnetic separator must be developed.

Application of small-angle neutron scattering to the study of forces between magnetically chained monodisperse ferrofluid emulsion droplets

2013 ◽  
Vol 47 (1) ◽  
pp. 41-52 ◽  
Author(s):  
N. Jain ◽  
C. K. Liu ◽  
B. S. Hawkett ◽  
G. G. Warr ◽  
W. A. Hamilton
Keyword(s):  
Magnetic Field ◽  
Neutron Scattering ◽  
Droplet Size ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Colloidal Particles ◽  
Optical Measurements ◽  
Magnetic Field Direction ◽  
Emulsion Droplets ◽  
The Magnetic Field

The optical magnetic chaining technique (MCT) developed by Leal-Calderon, Stora, Mondain-Monval, Poulin & Bibette [Phys. Rev. Lett.(1994),72, 2959–2962] allows precise measurements of force profiles between droplets in monodisperse ferrofluid emulsions. However, the method lacks anin situdetermination of droplet size and, therefore, requires a combination of separately acquired measurements of droplet chain periodicityversusan applied magnetic field from optical Bragg scattering and droplet diameter inferred from dynamic light scattering (DLS) to recover surface force–distance profiles between the colloidal particles. Compound refractive lens (CRL) focused small-angle neutron scattering (SANS) MCT should result in more consistent measurements of droplet size (form factor measurements in the absence of field) and droplet chaining period (from structure factor peaks when the magnetic field is applied), and, with access to shorter length scales, extend force measurements to closer approaches than possible by optical measurements. This article reports on CRL-SANS measurements of monodisperse ferrofluid emulsion droplets aligned in straight chains by an applied field perpendicular to the incident beam direction. Analysis of the scattering from the closely spaced droplets required algorithms that carefully treated resolution and its effect on mean scattering vector magnitudes in order to determine droplet size and chain periods to sufficient accuracy. At lower applied fields, scattering patterns indicate structural correlations transverse to the magnetic field direction owing to the formation of intermediate structures in early chain growth.

scholarly journals Tumor therapy by fast moving magnetic nanoparticle under low-frequency alternating magnetic field

2015 ◽  
Vol 08 (02) ◽  
pp. 1550008 ◽  
Author(s):  
Yangyang Liu ◽  
Zhiyu Qian ◽  
Jianhua Yin ◽  
Xiao Wang
Keyword(s):  
Magnetic Field ◽  
Tumor Cells ◽  
Magnetic Nanoparticle ◽  
Tumor Therapy ◽  
Low Frequency ◽  
Alternating Magnetic Field ◽  
Nanoparticle Concentration ◽  
Field Frequency ◽  
A New Technique ◽  
The Magnetic Field

Magnetic nanoparticle plays an important role in biomedical engineering, especially in tumor therapy. In this paper, a new technique has been developed by using the rapid moving magnetic nanoparticle under a low-frequency alternating magnetic field (LFAMF) to kill tumor cells. The LFAMF system which was used to drive magnetic nanoparticles (MNPs) was setup with the magnetic field frequency and power range at ∼ 10–100 Hz and ∼ 10–200 mT, respectively. During the experiment, the LFAMF was adjusted at different frequencies and power levels. The experimental results show that the liver tumor cells (HepG2) mixed with MNPs (10 μg/mL) became partial fragments when exposed in the LFAMF with different frequencies (∼ 10–100 Hz) and power (∼ 10–200 mT), and the higher the frequency or the power, the more the tumor cells were killed at the same magnetic nanoparticle concentration. Conclusion: Tumor cells were effectively damaged by MNPs under LFAMF, which suggests that they had great potential to be applied in tumor therapy.

scholarly journals Investigation and Modeling of the Magnetic Nanoparticle Aggregation with a Two-Phase CFD Model

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4871
Author(s):  
Péter Pálovics ◽  
Márton Németh ◽  
Márta Rencz
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticle ◽  
Domain Model ◽  
Cfd Model ◽  
Nanoparticle Aggregation ◽  
Two Phase ◽  
Particle Chain ◽  
Particle Chains ◽  
The Impact ◽  
The Magnetic Field

In this paper the magnetic nanoparticle aggregation procedure in a microchannel in the presence of external magnetic field is investigated. The main goal of the work was to establish a numerical model, capable of predicting the shape of the nanoparticle aggregate in a magnetic field without extreme computational demands. To that end, a specialized two-phase CFD model and solver has been created with the open source CFD software OpenFOAM. The model relies on the supposed microstucture of the aggregate consisting of particle chains parallel to the magnetic field. First, the microstructure was investigated with a micro-domain model. Based on the theoretical model of the particle chain and the results of the micro-domain model, a two-phase CFD model and solver were created. After this, the nanoparticle aggregation in a microchannel in the field of a magnet was modeled with the solver at different flow rates. Measurements with a microfluidic device were performed to verify the simulation results. The impact of the aggregate on the channel heat transfer was also investigated.

scholarly journals Investigation of the motion of magnetic nanoparticles in microfluidics with a micro domain model

2020 ◽  
Author(s):  
Péter Pálovics ◽  
Márta Rencz
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticle ◽  
Theoretical Calculations ◽  
Particle Interaction ◽  
Domain Model ◽  
Two Phase ◽  
Aggregation Procedure ◽  
Enzyme Substrate ◽  
The Magnetic Field ◽  
Good Agreement

AbstractIn this paper the magnetic nanoparticle (MNP) dynamics in a microfluidic device is investigated in the presence of an external magnetic field. The nanoparticles are used for enzyme-substrate reaction measurements, where the enzyme is immobilized to the surface of the nanoparticles. During the measurements the microreactors, called microchambers are filled up with the MNPs where the distribution of the nanoparticles significantly influences the results of the further reaction measurements. In this paper the procedure of the nanoparticle aggregation is investigated numerically in the microchamber in a micro domain simulation space. First the acting forces on the MNPs are examined from the different phenomena. An in-house numerical model is presented where the dynamics of several MNPs are simulated in the micro-size domain. This model is also embedded in the open source CFD software OpenFOAM. The theoretical calculations and the simulations show that the particle-particle interaction due to magnetization plays an important role during the aggregation procedure. The particles in the magnetic field cluster over the time into chains, which phenomenon is in good agreement with the literature. A theoretical model of the chain dynamics is also established, which is compared to the simulation results. The presented micro domain model was later used to improve an Eulerian-Eulerian based two-phase CFD model and solver, which is able to model the complete MNP aggregation procedure in the magnetic field in macroscopic domains.

scholarly journals Simulation of an Improved Microactuator with Discrete MSM Elements

2009 ◽  
Vol 635 ◽  
pp. 181-186 ◽  
Author(s):  
Berta Spasova ◽  
Hans Heinrich Gatzen
Keyword(s):  
Magnetic Field ◽  
Smart Materials ◽  
Parametric Design ◽  
Fem Analysis ◽  
Software Tool ◽  
Optimized Design ◽  
Checkerboard Pattern ◽  
Magnetic Shape Memory ◽  
New Class ◽  
The Magnetic Field

Magnetic Shape Memory (MSM) alloys are a new class of “smart” materials. In the martensite state, they exhibit a reversible strain due to a reorientation of twin variants, based on twin boundary motion driven by an external magnetic field occurring in the martensite state. This effect allows for the development of linear microactuators. This work presents the simulation results for the fabrication of a microactuator based on an MSM alloy with an optimized design. A stator element consists of a NiFe45/55 flux guide, two poles, and double-layer Cu coils wound around each pole for generating the magnetic field. The MSM material applied is NiMnGa. The integrated microactuator is subjected to dynamic simulation, using a “checkerboard” pattern to locally switch the magnetic properties when the relative permeability µr is changed. The model is described with the Ansys Parametric Design Language (APDL). Design, modeling, and simulation of the magnetic system including MSM material, are conducted by Finite Element Method (FEM) analysis using the software tool ANSYS™.

scholarly journals Testing the magnetoactive elastomer sample for compression with the test machine

2021 ◽  
Vol 2094 (4) ◽  
pp. 042064
Author(s):  
Andrey Minaev
Keyword(s):  
Magnetic Field ◽  
Testing Machine ◽  
Compression Modulus ◽  
Test Machine ◽  
Self Healing ◽  
Compression Force ◽  
Linear And Nonlinear ◽  
The Magnetic Field ◽  
Nonlinear Nature ◽  
Magnetoactive Elastomer

Abstract A sample of a magnetoactive silicone composite with ferromagnetic fillers is examined on a testing machine. The dependences of the change in the values of the moduli of longitudinal elasticity on deformation are plotted for various modes of compression of the sample. The characteristics of the linear and nonlinear dynamics of changes in the moduli of longitudinal elasticity are given as a function of the magnitudes of the deformations of the material during compression. Within the limits of deformation of the sample, which is 24% of its height, the moduli of longitudinal elasticity are linear. The nonlinear nature of the change in the compression modulus occurs when the sample is deformed over 40%. When the compression ratio of the sample was up to 72%, the compression modulus increased by a factor of 9 without the action of a magnetic field and by a factor of 22 under the action of a magnetic field. The influence of the magnetic field on the growth of the compression moduli with the increase in the compression force ranges is shown. The property of the material to self-healing (“shape memory”) was established after testing in the mode of maximum compression of ultimate loads.

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