ttp://en.wikipedia.org/wiki/Dielectrophoresis Dielectrophoresis (or DEP) is a phenomenon in which a force is exerted on a dielectric particle when it is subjected to a non-uniform electric field.This force does not require the particle to be charged. All particles exhibit dielectrophoretic activity in the presence of electric fields. However, the strength of the force depends strongly on the medium and particles' electrical properties, on the particles' shape and size, as well as on the frequency of the electric field. Consequently, fields of a particular frequency can manipulate particles with great selectivity. This has allowed, for example, the separation of cells or the orientation and manipulation of nanoparticles and nanowires.
Publications on dielectrophoresis go as far back as the 1950s, by Herbert Pohl. Recently, dielectrophoresis has been revived due to its potential in the manipulation of microparticles, nanoparticles and cells. Pohl wrote in his book defining dielectrophoresis as the translational motion of neutral matter caused by polarization effects in a nonuniform electric field. The phenomenological bases are catalogued below: The dielectrophoresis force can be seen only when particles are in nonuniform electric fields. Since the dielectrophoresis force does not depend on the polarity of the electric field, the phenomenon can be observed either with AC or DC excitation. Particles are attracted to regions of stronger electric field when their permittivity exceeds that of the suspension medium. When the permittivity of the medium is greater than that of the particles, the motion of the particles is to lesser electric field. DEP is most readily observed for particles with diameters ranging from approximately 1 to 1000 μm. Above 1000 μm, gravity overwhelms DEP; below 1 μm, Brownian motion overwhelms the DEP forces. Phenomena associated with dielectrophoresis are electrorotation and traveling wave dielectrophoresis (TWDEP). Dielectrophoresis can be enhanced using multiple frequencies, in what is known as multiple-frequency dielectrophoresis (MFDEP).
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ttp://en.wikipedia.org/wiki/Dielectrophoresis
Dielectrophoresis (or DEP) is a phenomenon in which a force is exerted on a dielectric particle when it is subjected to a non-uniform electric field.This force does not require the particle to be charged. All particles exhibit dielectrophoretic activity in the presence of electric fields. However, the strength of the force depends strongly on the medium and particles' electrical properties, on the particles' shape and size, as well as on the frequency of the electric field. Consequently, fields of a particular frequency can manipulate particles with great selectivity. This has allowed, for example, the separation of cells or the orientation and manipulation of nanoparticles and nanowires.
Publications on dielectrophoresis go as far back as the 1950s, by Herbert Pohl. Recently, dielectrophoresis has been revived due to its potential in the manipulation of microparticles, nanoparticles and cells.
Pohl wrote in his book defining dielectrophoresis as the translational motion of neutral matter caused by polarization effects in a nonuniform electric field. The phenomenological bases are catalogued below:
The dielectrophoresis force can be seen only when particles are in nonuniform electric fields.
Since the dielectrophoresis force does not depend on the polarity of the electric field, the phenomenon can be observed either with AC or DC excitation.
Particles are attracted to regions of stronger electric field when their permittivity exceeds that of the suspension medium.
When the permittivity of the medium is greater than that of the particles, the motion of the particles is to lesser electric field.
DEP is most readily observed for particles with diameters ranging from approximately 1 to 1000 μm. Above 1000 μm, gravity overwhelms DEP; below 1 μm, Brownian motion overwhelms the DEP forces.
Phenomena associated with dielectrophoresis are electrorotation and traveling wave dielectrophoresis (TWDEP). Dielectrophoresis can be enhanced using multiple frequencies, in what is known as multiple-frequency dielectrophoresis (MFDEP).
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