Optical Imaging of Magnetic Particle Cluster Oscillation and Rotation in Glycerol

Magnetic particles have been evaluated for their biomedical applications as a drug delivery system to treat asthma and other lung diseases. In this study, ferromagnetic barium hexaferrite (BaFe12O19) and iron oxide (Fe3O4) particles were suspended in water or glycerol, as glycerol can be 1000 times more viscous than water. The particle concentration was 2.50 mg/mL for BaFe12O19 particle clusters and 1.00 mg/mL for Fe3O4 particle clusters. The magnetic particle cluster cross-sectional area ranged from 15 to 1000 μμm2, and the particle cluster diameter ranged from 5 to 45 μμm. The magnetic particle clusters were exposed to oscillating or rotating magnetic fields and imaged with an optical microscope. The oscillation frequency of the applied magnetic fields, which was created by homemade wire spools inserted into an optical microscope, ranged from 10 to 180 Hz. The magnetic field magnitudes varied from 0.25 to 9 mT. The minimum magnetic field required for particle cluster rotation or oscillation in glycerol was experimentally measured at different frequencies. The results are in qualitative agreement with a simplified model for single-domain magnetic particles, with an average deviation from the model of 1.7 ± 1.3. The observed difference may be accounted for by the fact that our simplified model does not include effects on particle cluster motion caused by randomly oriented domains in multi-domain magnetic particle clusters, irregular particle cluster size, or magnetic anisotropy, among other effects.

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THE STUDY OF THE MAGNETIC BREAKDOWN EFFECT AS A FUNCTION OF ANGLE IN THE ORGANIC CONDUCTOR K- (BEDT-TTF)2Cu(NCS)2 IN HIGH MAGNETIC FIELDS

International Journal of Modern Physics B ◽

10.1142/s0217979202014401 ◽

2002 ◽

Vol 16 (20n22) ◽

pp. 3355-3359

Author(s):

I. MIHUT ◽

C. C. AGOSTA ◽

C. H. MIELKE ◽

M. TOKOMOTO

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Spin Splitting ◽

High Magnetic Fields ◽

Organic Conductor ◽

Cross Sectional ◽

Tank Circuit ◽

Quantum Oscillations ◽

Magnetic Breakdown ◽

Splitting Factor

The magnetic breakdown effect can be seen by the growth of new frequencies in the quantum oscillations in clean metals as a function of magnetic field. We have studied the variation of the amplitudes in the quantum oscillations in the resistance (the Shubnikov-de Haas effect) as a function of angle in the quasi-two dimensional-organic conductor κ-(BEDT-TTF)2Cu(NCS)2. The measurements were made by means of a radio frequency (rf) tank circuit (~ 50 MHz) at very high magnetic fields(50T-60T) and low temperature(500 mK). The geometry of the rf excitation we used excited in-plane currents, and therefore we measured the in-plane resistivity. In contrast to conventional transport measurements that measure the inter-plane resistivity, the in-plane resistivity is dominated by the magnetic breakdown frequencies. As a result we measured much higher breakdown frequency amplitudes than conventional transport experiments. As is expected, the angular dependence of the Shubnikov-de Haas frequencies have a 1/cosθ behavior. This is due to the change of the cross sectional area of the tubular Fermi surface as the angle with respect to the magnetic field is changed. The amplitude of the oscillations changes due to the spin splitting factor which takes into account the ratio between the spin splitting and the energy spacing of the Landau levels which also has 1/cosθ behavior. We show that our data agree with the semi-classical theory (Lifshitz-Kosevich formula).

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Railway Actuator Made of Magnetic Elastomers and Driven by a Magnetic Field

Polymers ◽

10.3390/polym10121351 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1351 ◽

Cited By ~ 2

Author(s):

Yasuhiro Umehara ◽

Yusuke Yamanaga ◽

Shota Akama ◽

Shunsuke Kato ◽

Shogo Kamoshita ◽

...

Keyword(s):

Magnetic Field ◽

Elastic Modulus ◽

Magnetic Fields ◽

Magnetic Particles ◽

Fine Particles ◽

Lateral Force ◽

Railway Vehicle ◽

Compression Tests ◽

Field Stress ◽

Magnetic Elastomers

We fabricated a mono-link using bimodal magnetic elastomers that demonstrate drastic changes in the elastic modulus by magnetic fields. The magnetic elastomer is bimodal consisting of large magnetic particles and nonmagnetic fine particles. The storage modulus for bimodal magnetic elastomers was altered from 2.2 × 105 to 1.7 × 106 Pa by a magnetic field of 500 mT. Compression tests up to a strain of 20% also revealed that the on-field stress for the bimodal magnetic elastomer was 1.24 times higher than the off-field stress. The bimodal magnetic elastomer was synthesized for the mono-link and was mounted on the bogie of a railway vehicle. A running test exhibited that the wheel lateral force was reduced by 20% by applying a magnetic field of 390 mT.

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Targeting Magnetic Nanoparticles in High Magnetic Fields for Drug Delivery Purposes

MRS Proceedings ◽

10.1557/proc-820-o3.8 ◽

2004 ◽

Vol 820 ◽

Cited By ~ 3

Author(s):

Ramazan Asmatulu ◽

Richard.O. Claus ◽

Judy S. Riffle ◽

Michael Zalich

Keyword(s):

Magnetic Field ◽

Drug Delivery ◽

Magnetic Nanoparticles ◽

Magnetic Fields ◽

Magnetic Particles ◽

Guidance System ◽

Test Results ◽

Test Parameters ◽

Magnetic Guidance ◽

The Magnetic Field

AbstractBiodegradable magnetic nanoparticles were synthesized using Poly(L-Lactic Acid) and magnetite nanoparticles (∼14 nm) at different dosages, and then these nanaoparticles (nanocomposites) and pure magnetic particles were targeted in external magnetic fields by changing the test parameters. The magnetic field test results showed that magnetic saturation, fluid speed, magnetic field distance and particle size were extremely effective for a magnetic guidance system that is needed for an effective drug delivery approach. Thus, it is assumed that such nanoparticles can carry drugs (chemotherapy) to be able to cure cancer tumors as well as many other diseases.

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Experiments and Numerical Implementation of a Boundary Value Problem Involving a Magnetorheological Elastomer Layer Subjected to a Nonuniform Magnetic Field

Journal of Applied Mechanics ◽

10.1115/1.4050534 ◽

2021 ◽

Vol 88 (7) ◽

Author(s):

Charles Dorn ◽

Laurence Bodelot ◽

Kostas Danas

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Boundary Value Problem ◽

Magnetic Particles ◽

Boundary Value ◽

Energetic Efficiency ◽

Iron Core ◽

Isotropic Layer ◽

Magnetorheological Elastomer ◽

Electromagnetic Coil

Abstract This study investigates experimentally and numerically the response of a magnetorheological elastomer (MRE) layer placed atop an electromagnetic coil. The MRE layer is deflected upon application of a current in the coil, which creates highly nonuniform magnetic fields. Isotropic and transversely isotropic layers (i.e., containing chains of magnetic particles) are tested experimentally, and the isotropic layer exhibits the largest deflection. To enhance the energetic efficiency of the model device, an iron core is introduced inside the electromagnetic coil, thereby leading to an increase in the resulting magnetic field near the center of the MRE layer. In parallel, the boundary value problem —including the MRE layer, the coil, the core (if present) and the surrounding air—is modeled numerically. For this, a magneto-mechanical, vector potential-based variational formulation is implemented in a standard three-dimensional finite element model at finite strains. For the material description, a recently proposed analytical homogenization-guided model is used to analyze the MRE in the “coil-only” configuration. It is then employed to predict the response of the layer in the “coil plus core” configuration, thus circumventing the need for a separate material characterization procedure. The proposed numerical simulation strategy provides a deeper understanding of the underlying complexity of the magnetic fields and of their interaction with the MRE layer. This study also reveals the importance of modeling the entire setup for predicting the response of MRE materials and, as a result, constitutes a step toward designing more efficient MRE-based devices.

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Experimental Investigation of Magnetic Particle Movement in Two-Phase Vertical Flow under an External Magnetic Field Using 2D LIF-PIV

Applied Sciences ◽

10.3390/app10113976 ◽

2020 ◽

Vol 10 (11) ◽

pp. 3976

Author(s):

Changje Lee ◽

Yong-Seok Choi

Keyword(s):

Magnetic Field ◽

External Magnetic Field ◽

Magnetic Particles ◽

Magnetic Particle ◽

Two Phase Flow ◽

Scattered Light ◽

Laser Sheet ◽

Phase Flow ◽

Particle Movement ◽

Two Phase

In this study, we experimentally investigated magnetic particle movement in two-phase flow under an external magnetic field. According to Faraday’s law, the alignment of a magnet is important for power generation. For high generation, it is important to understand how magnetic particles move in two-phase flow. The rotationality could be determined by observing a single particle; however, this is impossible due to the flow conditions. In this study, we estimated nonrotationality based on the vorticity. To eliminate scattered light and improve the signal-to-noise ratio, the laser-induced fluorescence particle image velocimetry technique was used. The solenoid nozzle has a hydraulic diameter of 3 mm. Its surface is covered with a coil with a diameter of 0.3 mm. The average diameter of a magnetic particle is 1.2 μm. The excitation and emission wavelengths are 532 and 612 nm, respectively. A thin laser sheet setup was configured. The laser sheet was illuminated on both sides to prevent shadows. The images were captured at 200 μm away from the wall and center of the nozzle. To estimate the decrease in vorticity, the theoretical and single-phase non-magnetic and magnetic particles are compared. The vorticity of magnetic particles is reduced by the external magnetic field.

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Theoretical Modeling and Simulations of Magnetic Fluids in Gradient Magnetic Fields

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.146-147.1510 ◽

2010 ◽

Vol 146-147 ◽

pp. 1510-1513

Author(s):

Xiao Ling Peng ◽

Xiao Yang ◽

Hai Biao Wei ◽

Rui Ping Yue ◽

Hong Liang Ge

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Field Gradient ◽

Magnetic Particles ◽

Magnetic Field Gradient ◽

Magnetic Fluids ◽

Gradient Distribution ◽

Particle Distributions ◽

The Right ◽

Pulsed Fields

When a magnetic field is applied to magnetic fluids (MF), various structures of MF are formed: chain-like structures in low fields, columnar, lamellar and striped structures in high fields, ellipsoidal structures in pulsed fields, and layered structures in rotating fields. The inner structures and particle distributions of MF in gradient magnetic fields are quite interesting, but very few works have been done on this. In the present study, the effects of magnetic field gradient on the structures of MF are investigated using a two-dimensional Monte Carlo simulation. The results show that a gradient distribution of magnetic particles is formed under gradient magnetic fields. Moreover, with increasing the field gradient, more magnetic particles are pushed to the right region and particle distribution changes from grass-like clusters to needle-like ones.

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Magnetostriction of Field-Structured Composites

MRS Proceedings ◽

10.1557/proc-785-d12.5 ◽

2003 ◽

Vol 785 ◽

Author(s):

James E. Martin ◽

Robert A. Anderson ◽

Gerald Gulley

Keyword(s):

Magnetic Field ◽

Magnetic Susceptibility ◽

Magnetic Fields ◽

Magnetic Particles ◽

Structural Phase ◽

Sensors And Actuators ◽

Demagnetizing Field ◽

New Class ◽

Self Consistent Field ◽

Principal Directions

ABSTRACTField-structured magnetic particle composites are an important new class of materials that have great potential as both sensors and actuators. These materials are synthesized by suspending magnetic particles in a polymeric resin and subjecting these to magnetic fields while the resin polymerizes. If a simple uniaxial magnetic field is used, the particles will form chains, yielding composites whose magnetic susceptibility is enhanced along a single direction. A biaxial magnetic field, comprised of two orthogonal ac fields, forms particle sheets, yielding composites whose magnetic susceptibility is enhanced along two principal directions. A balanced triaxial magnetic field can be used to enhance the susceptibility in all directions, and biased heterodyned triaxial magnetic fields are especially effective for producing composites with a greatly enhanced susceptibility along a single axis. Magnetostriction is quadratic in the susceptibility, so increasing the composite susceptibility is important to developing actuators that function well at modest fields. To investigate magnetostriction in these field-structured composites we have constructed a sensitive, constant-stress apparatus capable of 1 ppm strain resolution. The sample geometry is designed to minimize demagnetizing field effects. We have demonstrated field-structured composites with nearly 10,000 ppm strain, and have shown that at large magnetic fields a structural phase transition occurs within the composite. These experimental results are compared to microscopic, self-consistent field simulations of magnetostriction in these complex, disordered materials.

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Influence of the Magnetic Interaction among Particles on Distributions of Magnetic Fluids Using Computer Simulations

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.150-151.1595 ◽

2010 ◽

Vol 150-151 ◽

pp. 1595-1598

Author(s):

Xiao Ling Peng ◽

Hai Biao Wei ◽

Xiao Yang ◽

Rui Ping Yue ◽

Hong Liang Ge

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Magnetic Particles ◽

Particle Distribution ◽

Magnetic Field Gradient ◽

Magnetic Interaction ◽

Magnetic Fluids ◽

Colloidal Dispersion ◽

Gradient Distribution ◽

Particle Distributions

Magnetic fluid is a stable colloidal dispersion of ferromagnetic particles in a liquid carrier. Once a magnetic field is applied to magnetic fluids (MF), various structures of MF are formed. A detailed understanding of structures and particle distributions in gradient magnetic fields is much important. But very few works have been done on this. In the present study, the effects of magnetic field gradient and magnetic interaction among magnetic particles on the structures of MF are investigated using a two-dimensional Monte Carlo simulation. The results show that a gradient distribution of magnetic particles is formed under gradient magnetic fields. However, as the interaction between magnetic particles increases, the distribution gradient decreases, accompanied by the formation of chain-like clusters. Moreover, with increasing the magnetic interaction, particle distribution changes from grass-like clusters to needle-like ones.

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Integrated lab-on-chip biosensing systems based on magnetic particle actuation – a comprehensive review

Lab on a Chip ◽

10.1039/c3lc51454d ◽

2014 ◽

Vol 14 (12) ◽

pp. 1966-1986 ◽

Cited By ~ 159

Author(s):

Alexander van Reenen ◽

Arthur M. de Jong ◽

Jaap M. J. den Toonder ◽

Menno W. J. Prins

Keyword(s):

Magnetic Fields ◽

Magnetic Particles ◽

Magnetic Particle ◽

Comprehensive Review ◽

Lab On Chip ◽

Diagnostic Assays ◽

On Chip

A review on the use of magnetic particles that are actuated by magnetic fields for integrated lab-on-chip diagnostic assays.

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Magnetic field frequency optimisation for MFL imaging using QWHE sensors

Insight - Non-Destructive Testing and Condition Monitoring ◽

10.1784/insi.2020.62.7.396 ◽

2020 ◽

Vol 62 (7) ◽

pp. 396-401

Author(s):

J M Watson ◽

C W Liang ◽

J Sexton ◽

M Missous

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Field Strength ◽

Power Consumption ◽

Applied Magnetic Field ◽

Magnetic Particles ◽

Permanent Magnets ◽

Low Frequency ◽

Step Size ◽

Lift Off

Magnetic particle and other magnetic flux leakage (MFL)-based methods for the detection and evaluation of surfacebreaking flaws in ferromagnetic materials typically use high-strength (∼0.5 T RMS) low-frequency (≤50 Hz) magnetic fields. The rationale behind this is the ready availability of strong permanent magnets and mains power for highstrength electromagnets. This high field strength is needed to saturate the sample and compensate for the insensitivity of magnetic particles, silicon Hall sensors, coils and other magnetic transducers. Consequently, the frequency of the applied magnetic field is typically limited to ≤50 Hz and does not consider the frequency response of the material under test (some MFL applications use this low frequency to detect subsurface or flaws on the backwall). In this study, a probe consisting of a quantum well Hall-effect (QWHE) sensor, an illuminating electromagnet and sensor circuitry was controlled using an automated XYZ scanner with an x-y measurement step size (ie magnetic image pixel size) of 100 microns. This probe was used to apply magnetic fields of various frequencies (DC to 1 kHz) and field strengths (5 mT to 100 mT) to ascertain a frequency and field range best suited to detecting 10 mm- and 11 mm-long longitudinal surface-breaking toe cracks in ground mild steel welds. A lift-off distance of <1 mm was controlled using a proximity laser and a z-direction motor module to autonomously control the probe lift-off and conform to sample geometry. This study found that an applied magnetic field with a frequency of 800 Hz and a field strength of 10 mT RMS was optimal under the constraint of power consumption, based on the ratio of MFL responses from the two flaws and the weld. It was found that other frequency field combinations had comparable or higher detection but were discounted as they had substantially higher power consumption.

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