The Experts below are selected from a list of 891 Experts worldwide ranked by ideXlab platform
Xiangchun Xuan - One of the best experts on this subject based on the ideXlab platform.
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On-chip manipulation of Nonmagnetic Particles in paramagnetic solutions using embedded permanent magnets
Microfluidics and Nanofluidics, 2012Co-Authors: Junjie Zhu, Litao Liang, Xiangchun XuanAbstract:This study develops a method for embedding permanent magnets into poly(dimethylsiloxane) (PDMS)-based microfluidic chips. Magnets can be brought very close to the planar microchannels for enhanced magnetic field and field gradients, which enables on-chip continuous-flow manipulation of Nonmagnetic Particles in typical paramagnetic solutions. We performed a systematic study of the transport of polystyrene Particles suspended in manganese (II) chloride (MnCl2) solutions through a rectangular microchannel. Owing to their smaller magnetization than the suspending fluid, Particles experience negative magnetophoresis and are deflected away from the magnet. The effects of Particle position (relative to the magnet), Particle size, MnCl2 salt concentration, and fluid flow velocity on the horizontal magnetophoretic deflection are examined using a combined experimental and theoretical approach. The experimental results agree quantitatively with the predictions of an analytical model. The demonstrated Nonmagnetic Particle deflection may be used with the potential to focus and sort cells in lab-on-a-chip for bio-applications.
D. Jamon - One of the best experts on this subject based on the ideXlab platform.
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Initial susceptibility, flow curves, and magneto-optics of inverse magnetic fluids
Physical Review E, 2003Co-Authors: M. Raşa, Albert P. Philipse, D. JamonAbstract:We introduce inverse magnetic fluids, consisting of gibbsite [Al(OH)(3)] platelets and alumina (Al2O3) spheres dispersed in a magnetic fluid, studied together with silica (SiO2) dispersions based on the same magnetic fluid matrix. Atomic force microscopy, optical microscopy, and alternate gradient magnetometry confirm the remarkable stability of the samples. Optical microscopy shows aggregation of Nonmagnetic spheres, which, surprisingly, strongly depends on the concentration of the magnetic fluid rather than the concentration of Nonmagnetic Particles. Our model for the initial susceptibility of inverse magnetic fluids agrees very well with experimental data for systems containing spherical Particles. The flow curves in an external magnetic field are strongly influenced by the aggregation of Nonmagnetic Particles or preformed Nonmagnetic Particle clusters, and by their disruption due to the shear flow. Static linear magnetobirefringence and magnetodichroism of all samples are investigated both experimentally and theoretically. These effects, which occur in all magnetic fluids, can be enhanced by the additional anisotropy due to the magnetic holes. The experiments we performed showed that, at a wavelength of 820 nm, the magnetodichroism is increased while the magneto-birefringence decreases when Nonmagnetic Particles were dispersed in the magnetic fluid. Magneto-birefringence is expected to be increased at large enough wavelengths only.
Junjie Zhu - One of the best experts on this subject based on the ideXlab platform.
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On-chip manipulation of Nonmagnetic Particles in paramagnetic solutions using embedded permanent magnets
Microfluidics and Nanofluidics, 2012Co-Authors: Junjie Zhu, Litao Liang, Xiangchun XuanAbstract:This study develops a method for embedding permanent magnets into poly(dimethylsiloxane) (PDMS)-based microfluidic chips. Magnets can be brought very close to the planar microchannels for enhanced magnetic field and field gradients, which enables on-chip continuous-flow manipulation of Nonmagnetic Particles in typical paramagnetic solutions. We performed a systematic study of the transport of polystyrene Particles suspended in manganese (II) chloride (MnCl2) solutions through a rectangular microchannel. Owing to their smaller magnetization than the suspending fluid, Particles experience negative magnetophoresis and are deflected away from the magnet. The effects of Particle position (relative to the magnet), Particle size, MnCl2 salt concentration, and fluid flow velocity on the horizontal magnetophoretic deflection are examined using a combined experimental and theoretical approach. The experimental results agree quantitatively with the predictions of an analytical model. The demonstrated Nonmagnetic Particle deflection may be used with the potential to focus and sort cells in lab-on-a-chip for bio-applications.
B. E. Kashevsky - One of the best experts on this subject based on the ideXlab platform.
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Nonmagnetic Particles in magnetic fluid: Reversal dynamics under rotating field
Physics of Fluids, 1997Co-Authors: B. E. KashevskyAbstract:The simultaneous action of magnetic and hydrodynamic forces responsible for the dynamic behavior of Nonmagnetic Particle assemblies within magnetic colloid (magnetic fluid) is investigated for the case of a pair of spherical Particles in a rotating magnetic field. The antisymmetric viscous stresses that exist in magnetic fluid due to colloidal ferroParticle internal rotation are taken into account alongside Particle–Particle magnetic and hydrodynamic interactions. On each Particle the internal rotation produces a couple acting in the direction opposite to the field rotation direction. The hydrodynamic interaction among rotating Particles results in a global couple which acts to meet the rotating field and opposes the couple of magnetic Particle–Particle interaction. The antisymmetric stresses grow with field frequency, and at some frequency value the pair-field co-rotation gives way to the counter-rotation. It is shown that the pair motion is sensitive to the Particle surface conditions, because of fast g...
Nipu Modak - One of the best experts on this subject based on the ideXlab platform.
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Influence of operating parameters in Particle spreading, separation, and capturing in a hybrid free flow magnetophoretic bio-separator
Physics of Fluids, 2020Co-Authors: Abhishek Samanta, Nipu ModakAbstract:In clinical applications, magnetic bead-based analyte separation has attracted interest over other types of separation techniques in the microfluidic protocol. The objective of the present study is to separate two different types of magnetic and one type of Nonmagnetic Particles from each other simultaneously with minimum cross-contamination in a microchannel. A numerical study is carried out for characterizing one hybrid microfluidic device. The device works on the principle of split-flow thin fractionation, field-flow fractionation, and free flow magnetophoresis. The geometry of the microfluidic bioreactor had been established by Samanta et al. in 2017, whereas the present research emphasized the impact of operating parameters in Particle spreading, separation, and capture in the hybrid free flow magnetophoretic device. The impact of magnetic and fluidic forces on transport, separation, and capture of the three different types of Particles is analyzed. The performance of the microfluidic device is checked by capture efficiency and separation indices for different operating conditions. Transport of the three different types of microspheres in the microchannel is prescribed following an Eulerian–Lagrangian model by using an in-house code. Two types of magnetic Particles of diameters 2 µm and 1 µm and one Nonmagnetic Particle of 0.5 µm diameter are used. Some group variables comprising of magnetic and fluidic parameters are found as an exclusive function of capture efficiency and separation index. In addition, from curve fitting, the universal dependence of capture efficiency and separation index on the various group variables is recognized for different curves with a reasonably high degree of compliance.
