Non-uniform spatial distributions of both the magnitude and phase of AC electric fields determine dielectrophoretic forces

Wang, X

doi:10.1016/0304-4165(94)00146-o

Cited by 55 publications

(40 citation statements)

References 22 publications

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“…8,15 Depending on the dielectric properties of the cells relative to their suspending medium, these forces can be positive or negative, directing the cells toward strong or weak electrical field regions, respectively. 8,15,21 12,17,[22][23][24] differential DEP forces can be applied to drive their separation into purified cell subpopulations. 14,[16][17][18][19][20][25][26] A recently developed technique, dielectrophoretic-field-flow fractionation (DEP-FFF), has been demonstrated to exhibit a high and electrically controllable discrimination for cell separation.…”

Section: Introductionmentioning

confidence: 99%

Cell Separation by Dielectrophoretic Field-flow-fractionation

et al. 2000

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Dielectrophoretic field-flow-fractionation (DEP-FFF) was applied to several clinically relevant cell separation problems, including the purging of human breast cancer cells from normal T-lymphocytes and from CD34 + hematopoietic stem cells, the separation of the major leukocyte subpopulations, and the enrichment of leukocytes from blood. Cell separations were achieved in a thin chamber equipped with a microfabricated, interdigitated electrode array on its bottom wall that was energized with AC electric signals. Cells were levitated by the balance between DEP and sedimentation forces to different equilibrium heights and were transported at differing velocities and thereby separated when a velocity profile was established in the chamber. This bulk-separation technique adds cell intrinsic dielectric properties to the catalog of physical characteristics that can be applied to cell discrimination. The separation process and performance can be controlled through electronic means. Cell labeling is unnecessary, and separated cells may be cultured and further analyzed. It can be scaled up for routine laboratory cell separation or implemented on a miniaturized scale.Modern cell separation techniques 1,2 have been fundamental to many advances in cell biology, molecular genetics, biotechno-logical production, clinical diagnostics, and therapeutics. The most common of these techniques, centrifugation, 2 electrophoresis, 3 and both fluorescence-(FACS) 4 and magnetic-activated-cell sorting (MACS), 5-6 take advantage of differences in cell density, electrical charge, and immunological surface markers. Using these methods, investigators and clinicians are able to deplete particular cell populations (e.g., purge tumor cells from stem cell transplants) or enrich them (e.g., purify CD34 + stem cells from human blood).As these technologies have reached maturity, however, it has become more difficult to make fundamental improvements in separation resolution, cell purity, sample size, and device cost and portability. Therefore, novel physical methods by which different cell types may be discriminated and selectively manipulated are desirable. Besides offering additional avenues for cell identification, such methods should, ideally, allow us to enhance cell separation, exploit integrated microfluidic methods, separate microliter-size samples, reduce cost, and develop portable separation devices. To this end, cell dielectric properties have been explored through dielectrophoresis (DEP) and other AC electro-kinetic effects 7-15 for developing cell separation techniques. [16][17][18][19][20] Dielectrophoretic forces occur on cells when a nonuniform electrical field interacts with fieldinduced electrical polarization. 8,15 Depending on the dielectric properties of the cells relative to their suspending medium, these forces can be positive or negative, directing the cells toward strong or weak electrical field regions, respectively. 8,15,21 12,17,[22][23][24] differential DEP forces can be applied to drive their separation into puri...

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Section: Introductionmentioning

confidence: 99%

Cell Separation by Dielectrophoretic Field-flow-fractionation

et al. 2000

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“…The 'polynomial' design, shown in figure 1, has been described in the literature [22] and its properties studied experimentally and theoretically [23]. This design produces not only steep gradients at the high-field points but also steep gradients directed towards a low-field 'trap' in the centre.…”

Section: Electrodesmentioning

confidence: 99%

Dielectrophoretic investigations of sub-micrometre latex spheres

Green

Morgan

1997

J. Phys. D: Appl. Phys.

108

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Abstract.A non-uniform AC electric field induces a motion in polarizable particles, called dielectrophoresis. The force responsible for this motion is governed by the dielectric properties both of the suspending medium and of the particles, as well as the geometry of the field. The dielectrophoretic properties of sub-micrometre latex spheres have been studied using micro-fabricated electrode structures. The electric field geometry for electrodes used in the measurements has been solved using numerical analysis. Measurements of the dielectrophoretic properties of the spheres have been made over a range of medium conductivities and applied field frequencies and strengths. Comparisons between the observed behaviour and that expected from theory are presented.

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“…By contrast, traveling-wave dielectrophoresis relies on the out-of-phase component of the induced dipole moment and on phase nonuniformity, that is, the secondary component of Eq. (2.1) [47]. Unlike DEP, the electrophoretic phenomena vanish in the absence of a net charge on the particle or in an alternating field [9].…”

Section: Dielectrophoresis (Dep)mentioning

confidence: 99%

“…Earlier research work indicated that a particle in a nonuniform AC electric field experiences DEP forces that are derived from interactions between the spatial heterogeneity of the magnitude and the phase of the field with the in-phase and out-of-phase components of the induced dipole moment [47]. The time-averaged DEP force ⟨F(t)⟩ exerted on a dielectric particle due to an imposed electric field, E, can be approximated in terms of dipole effects as [9,47,48] …”

Section: Dielectrophoresis (Dep)mentioning

confidence: 99%

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Micro and Nano Manipulation and Assembly by Optically Induced Electrokinetics

Lai

et al. 2015

Micro‐ and Nanomanipulation Tools

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IntroductionIn the past 25 years, integrated circuit (IC) and microelectromechanical systems (MEMSs) technologies have moved much beyond the microdomain, and into the submicro-, nanoscopic, and, even, the molecular scales. Today, we have the capability to fabricate, manipulate, and assemble matters at the micro-, nano-, or molecular scales. This progress into "seeing" and manipulating matters that are smaller than visible light wavelength scale is impacting a range of fields including semiconductor physics, biological studies, pharmaceutical development, and many other scientific and technological applications. A range of new methods to generate physical forces have been developed in the process. For example, mechanical forces can now be applied to micro-, nano-, and biological entities using atomic force microscope probes [1], microgrippers [2], or pipettes [3]. However, disadvantages of these approaches, including inflection of mechanical damages on objects being manipulated and their relatively low manipulation speed, make manipulation of large quantities of objects difficult. In order to address these disadvantages, noncontact or noninvasive methods for micro-, nano-, and biological manipulation have also been explored in the past two decades.Manipulation devices based on magnetic forces [4], acoustic waves [5,6], hydrodynamic flows [7], light waves [8], or electrokinetic forces [9] are among the major noninvasive technologies available today. Each of them has its own advantages and disadvantages. Methods based on magnetic fields need premodification on objects with magnetic beads which constrains their application domain. In addition, movement controlled by permanent magnets is not precise enough for many proposed applications. Also, the high resistance of the magnetic coil generates significant heat during manipulation [10]. Acoustic traps show good selectivity but cannot achieve parallel manipulation of single entities. Microfluidic devices exploiting hydrodynamic flows are suitable for cell population sorting, but have difficulties in trapping or controlling specific single objects.Electrokinetic forces generated from patterned electrodes capable of inducing the desired spatial distribution of electric field have been exploited to control

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Non-uniform spatial distributions of both the magnitude and phase of AC electric fields determine dielectrophoretic forces

Cited by 55 publications

References 22 publications

Cell Separation by Dielectrophoretic Field-flow-fractionation

Cell Separation by Dielectrophoretic Field-flow-fractionation

Dielectrophoretic investigations of sub-micrometre latex spheres

Micro and Nano Manipulation and Assembly by Optically Induced Electrokinetics

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