Orientation of Euglena by radio-frequency fields

Griffin, Jasper; Stowell, Robert E.

doi:10.1016/0014-4827(66)90487-3

Cited by 35 publications

(17 citation statements)

References 5 publications

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“…(15). Hence, the electric potential outside the layered particle is identical from that of a homogenous sphere.…”

Section: The Dep-shell Modelmentioning

confidence: 91%

“…At low and high frequency, the long axis of the cell will always be aligned parallel to the electric field as the dipole moment across the long axis trumps the short axis at these two frequency extremes. At intermediate frequencies, however, the cell can sometimes be observed to flip spontaneously to a new orientation as one induced dipole moment becomes dominant over another axis [15]. The depolarization factor models frequency dependent polarization for the three non-spherical axes.…”

Section: Modeling Non-spherical Cellsmentioning

confidence: 98%

“…The induced charge along this axis has the greatest effective dipole moment and will exert the greatest torque on the particle. As the frequency is increased and the long axis dipole begins to disperse, the particle will rotate 90 degrees and align perpendicular to the field [15]. To account for differing polarization along each axis, we introduce a term known as the depolarization factor, A a , for the axis a, defined as the elliptical integral [16],…”

Section: Modeling Non-spherical Cellsmentioning

confidence: 99%

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Cellular dielectrophoresis: Applications to the characterization, manipulation, separation and patterning of cells

2011

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Over the past decade, dielectrophoresis (DEP) has evolved into a powerful, robust and flexible method for cellular characterization, manipulation, separation and cell patterning. It is a field with widely varying disciplines, as it is quite common to see DEP integrated with a host of applications including microfluidics, impedance spectroscopy, tissue engineering, real-time PCR, immunoassays, stem-cell characterization, gene transfection and electroporation, just to name a few. The field is finally at the point where analytical and numerical polarization models can be used to adequately describe and characterize the dielectrophoretic behavior of cells, and there is ever increasing evidence demonstrating that electric fields can safely be used to manipulate cells without harm. As such, DEP is slowly making its way into the biological sciences. Today, DEP is being used to manipulate individual cells to specific regions of space for single-cell assays. DEP is able to separate rare cells from a heterogeneous cell suspension, where isolated cells can then be characterized and dynamically studied using nothing more than electric fields. However, there is need for a critical report to integrate the many new features of DEP for cellular applications. Here, a review of the basic theory and current applications of DEP, specifically for cells, is presented.

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“…(15). Hence, the electric potential outside the layered particle is identical from that of a homogenous sphere.…”

Section: The Dep-shell Modelmentioning

confidence: 91%

Section: Modeling Non-spherical Cellsmentioning

confidence: 98%

Section: Modeling Non-spherical Cellsmentioning

confidence: 99%

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Cellular dielectrophoresis: Applications to the characterization, manipulation, separation and patterning of cells

2011

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“…Depending upon the properties of the particle and medium, there may be one or two "turnover" frequencies where the orientation changes from parallel to perpendicular to the field [66,67]. Not only the properties of the particle but also those of the medium are important, and these appear in the form of their time constants ε/σ [1].…”

Section: Orientationmentioning

confidence: 99%

Particle patterning using fluidics and electric fields

Arnold

2008

IEEE Trans. Dielect. Electr. Insul.

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Electric-field manipulation of micro-particles in suspension can create patterns via a number of particle forces and fluid flows. These effects are assessed for their suitability for down-scaling to form nano-patterns such as may be incorporated into structured nano-composites. Consideration is given not only to the assembly of field-aligned chains or wires, but also to methods that can give cross-field assembly and even 2-D patterns or crystals. Dielectrophoresis is often the dominant driving force behind particle assembly, but other dipole-dipole interactions and also electrically-driven fluid flows are increasingly recognized as significant or dominant. Orientation of nonspherical particles in frequency-selectable directions is also possible. Estimates for the threshold field strengths required for using these effects to handle nano-particles are considered. Finally the use of media with modified permittivity to increase the fieldinduced forces or to optimize the selectivity of particle incorporation is discussed. Index Terms -Composite; Artificial tissue; Dielectrophoresis; Electroosmosis W. Michael Arnold (A'95-SM'00) was raised in Yorkshire, U.K. He received the B.A. degree from Cambridge University in 1974, and the M.Sc. and Ph.D. (EE) degrees from the University of Wales.After developing the technique of electro-rotation and also teaching in Biotechnology at the University of Würzburg, Germany, he received the Dr. rer. nat. habil. degree from that University in 1993. In 1995 he chaired the IAS session on "Biological Applications of Electrostatics", and in 2001 he cochaired a DEIS workshop on "Fast Field Effects in Biosystems". Present research interests are nanoassembly, microfluidic devices and bio-impedance spectroscopy.

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“…Best known among them are the collections of cells at the electrodes (Pohl and Hawk, 1966;Mason and Townsley, 1971) and the alignment of cells in form of "pearl chains" along the lines of the electric field (Teixeira-Pinto et al, 1960;Furedi and Ohad, 1964;Glaser et al, 1979), a procedure which is used in recent times as prerequisite for cell fusion by electric pulses (Scheurich et al, 1980;Zimmermann, 1982). Moreover, orientation of prolonged particles perpendicular or parallel to the field lines in dependence upon the frequency is observed in many systems (Griffin and Stowell, 1960;Teixeira-Pinto et al, 1960;Furedi and Ohad, 1964} or rotation of cells in alternating (Furedi and Ohad, 1964;Mischel and Lamprecht, 1980;Holzapfel et al, 1982) or rotating external fields (Arnold and Zimmermann, 1982;Mischel et al, 1982). All these effects can be summarized under dietectrophoresis (DEP} the action of alternating nonuniform fields on neutral matter (Pohl, 1978).…”

Section: Introductionmentioning

confidence: 96%

Dynamic and static cord-structure: A new dielectrophoretic phenomenon

et al. 1983

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During the dielectrophoresis of ceils or other particles it is observed that unusual distributions of the cells appear on the floor of the test chamber. In certain narrow frequency ranges, the distributions are cord-like, with the "cords" running more or less parallel to the electrode faces, but also developing highly branched structures. It is observed that the cells within the cords form "pearl-chains" along the field lines and across the cords. Within the cords, the cells move actively in spiralized paths. This the dynamic cord-structure is considered to be due to the combined action of negative dieleetrophoresis, Brownian motion, and gravity. Outside the conditions requisite for dynamic cord formation, the cells are seen to assume conformations reflective of simple negative dielectrophoresis which merely causes them to amass into regions of low field strength. The theory for the effects is presented, together with experimental evidence for the kinetic behavior of the dynamic cord effect.

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Orientation of Euglena by radio-frequency fields

Cited by 35 publications

References 5 publications

Cellular dielectrophoresis: Applications to the characterization, manipulation, separation and patterning of cells

Cellular dielectrophoresis: Applications to the characterization, manipulation, separation and patterning of cells

Particle patterning using fluidics and electric fields

Dynamic and static cord-structure: A new dielectrophoretic phenomenon

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