Biomedical Engineering Reference
In-Depth Information
the particles from it. It is a strikingly different situation from the one dealt with in
the preceding part were both in the positive and in the negative dielectrophoresis
regimes, particles were confined close to the grating surface. But the use of positive
DEP regime is not trivial either: particles not initially present in the channel tend to
be collected in it, increasing the concentration. Furthermore, electrohydrodynamic
flows develop on the tips of the electrodes generating recirculations of particles
around the trapping zones.
In Figure 10.22, one can see a typical sequence of the migration of the particles
(in that particular case 0.5-
m
m latex), as the potential is switched from one pair of
electrodes to the other.
The particles indeed move from one dielectrophoretic trap on one pair of elec-
trodes to the next one on the other pair when switching the field from one plate to
the other. The analysis of the experimental results is of the same nature as in the
Brownian ratchet experiment. The expected velocity regimes
V
= 0 or
V
=
V
opt
are
indeed observed for two different sizes [67]. Although the dielectrophoretic behav-
iors are more complex in this geometry than they are in the Brownian ratchets case,
the observed filter effect along with the high velocities reached by the beads make
this realization highly promising in separations problems. For this particular device
as for many others presented here, an improvement in the performances will come
from a better control of the microfluidics.
References
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Faraday Soc
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Intermolecular and Surface Forces
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Zeta Potential in Colloid Science,
New York: Academic Press, 1988.
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phénomènes corrélatifs,”
Bull. Int. Univ. Sci. Cracovie
, Vol. 8, 1903, pp. 182-200
[5] Russel, W. B., D. A. Saville, and S. R. Schowalter,
Colloidal Dispersions,
Cambridge, U.K.:
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20, 1996, pp. 3858-3861.
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94, 1996, pp. 1-66.
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[10] Rodbard, D., and A. Chrambac, “Unified Theory for Gel Electrophoresis and Gel Filtra-
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[11] Slater, G. W., C. Desruisseaux, and S. J. Hubert, “DNA Separation Mechanisms During
Electrophoresis,” in
Methods in Molecular Biology, Vol. 162: Capillary Electrophoresis of
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