Particle Trajectories in Field-Flow Fractionation and SPLITT Fractionation Channels

Williams, P. Stephen

doi:10.1080/01496399408002468

Cited by 29 publications

(5 citation statements)

References 68 publications

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“…Due to the possibility of increasing the magnetic field-induced particle migration velocity, reducing the length of device is feasible. For constant particle migration velocity, the present general theory agrees well with the previous theory for large aspect ratio devices, and much experimental and numerical validation for the previous theory can be found in the literature [4,6,22]. Here, we propose a magnetic SPLITT, which is similar to the device designed by Fuh and his coworkers [3,20,23], but with short aspect ratio.…”

Section: An Example Of Scale-up Of a Magnetic Splitt Devicesupporting

confidence: 86%

“…particles have negligible effect on the flow field, the Navier-Stokes equations are solved for the steady flow in the channel. The particle trajectory is determined by solving equations (9) and (22), because the particles respond instantaneously to the change of fluid motion. In this paper, results from a code written in Fortran 90, using the classical SIMPLE algorithm, for solving Navier-Stokes equations are presented.…”

Section: Numerical Simulation and Discussionmentioning

confidence: 99%

“…a parabolic velocity profile and streamlines parallel to each other. In the theory developed below, we relax the restriction of L/W>>1 which was assumed in the previous theory [4,5,7].…”

Section: General Theory Of Splitt Fractionationsmentioning

confidence: 99%

“…Split-flow thin (SPLITT) fractionation is a technique whereby an external field is used to separate macromolecules, colloids, cells and particles in sample solutions. It is widely used in biological, medical, environmental and industrial applications [1][2][3][4][5][6][7]. A schematic of a typical SPLITT fractionation system is shown in figure 1 (where the magnetic field is shown).…”

Section: Introductionmentioning

confidence: 99%

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General theory for flow optimisation of split-flow thin fractionation

Zhang

Emerson

Reese

2003

Journal of Chromatography A

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Recently, magnetic split-flow thin (SPLITT) fractionation has been developed to separate macromolecules, colloids, cells and particles. However, the previous theory, developed for an infinitely long channel, needs to be improved to consider the flow transit regimes at both inlet and outlet. In this paper, we describe a new approach to optimising flow-rates for particle separation which considers the effect of flow transit region. Surprisingly, the critical particle migration velocities derived by the present theory are identical to the previous simplified theory. Therefore, the previous simplified theory may have wider application than might have been expected. As a test of our theory, a numerical simulation based on solving Navier-Stokes equations has also been carried out for a magnetic SPLITT device. The trajectory of a particle with the critical migration velocity is exactly as expected by our theory. Following experimental validation, this work will facilitate the design of new SPLITT fractionation systems with smaller aspect ratio.

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Section: An Example Of Scale-up Of a Magnetic Splitt Devicesupporting

confidence: 86%

Section: Numerical Simulation and Discussionmentioning

confidence: 99%

“…a parabolic velocity profile and streamlines parallel to each other. In the theory developed below, we relax the restriction of L/W>>1 which was assumed in the previous theory [4,5,7].…”

Section: General Theory Of Splitt Fractionationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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General theory for flow optimisation of split-flow thin fractionation

Zhang

Emerson

Reese

2003

Journal of Chromatography A

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“…This system has been demonstrated for a variety of particles ranging in size from 5 nm to several microns. [17][18][19][20][21][22][23][24][25][26][27][28][29] SPLITT does not require filters or a ''stationary phase'' to accomplish these separations. The SPLITT system, because of its ability to operate continuously, could potentially be used to separate and prepare nanoparticles with a variety of applications including: biological labelling, 30 DNA delivery, 31,32 cosmetics, 33 drug delivery vehicles, 34,35 carbon nanotubes, 36,37 composite materials, 38 and others.…”

Section: Introductionmentioning

confidence: 99%

A microfabricated electrical SPLITT system

2006

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A growing need for methods to analyze and prepare monodisperse nanoparticles on an industrial scale exists and may be solved by the application of split flow thin fractionation (SPLITT) at the microscale. Microfluidic systems of this type have the ability to separate nanoparticles with high precision in a continuous manner. A miniaturized SPLITT system can be fabricated using standard microfabrication technologies, works in a continuous mode, and can be used as a sample preparation instrument in a micro-total-analysis-system (micro-TAS). In this paper, a miniaturized electrical SPLITT system, which separates particles continuously based on electrophoretic mobility, has been characterized. The advantages of miniaturization have been elucidated. The various aspects of the micro SPLITT system discussed in this paper can be broadly classified into: micro SPLITT system design, fluidics modeling to refine the splitter arrangements, and experimental characterization of the SPLITT system. The design of the micro SPLITT system has been elucidated focusing on the two designs that were implemented. Fluid modeling, used to arrive at a new SPLITT design, was done using a commercially available CFD package to investigate behavior of the fluid in the microchannel with various splitter arrangements. Testing was done with nanoparticles of varying diameter and electrophoretic mobilities to verify the modeling results and demonstrate functionality of the SPLITT system. Particles eluted from both outlets of the SPLITT system were characterized using AFM and SEM to verify the function of the system.

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Effect of flowrate and ionic strength on retention of nonporous micron-sized silica gel particles in gravitational field-flow fractionation

2005

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Abstract. Retention of nonporous micron-sized silica gel particles in gravitational field-flow fractionation (GFFF) was investigated with respect to the activity of the hydrodynamic lift-forces and surface forces. The hydrodynamic lift-forces act near the channel wall in the same direction as repulsive electrostatic forces against the gravity so that the particles are focused. Although a complete quantitative description of the hydrodynamic lift-forces, which would enable prediction of the retention time, is not yet available, the experiments show that the magnitude of both forces is comparable with the particle effective weight and that the forces can be used for efficient separation of micron-sized particles. Higher ionic strengths of the carrier liquid attained by addition of NaCl decrease the repulsive electrostatic force and dramatically influence retention of the particles, yet to be reported in GFFF. o 1996 John Wiley & Sons, Inc.

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Particle Trajectories in Field-Flow Fractionation and SPLITT Fractionation Channels

Cited by 29 publications

References 68 publications

General theory for flow optimisation of split-flow thin fractionation

General theory for flow optimisation of split-flow thin fractionation

A microfabricated electrical SPLITT system

Effect of flowrate and ionic strength on retention of nonporous micron-sized silica gel particles in gravitational field-flow fractionation

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