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Transient electrophoretic motion of a charged particle through a converging–diverging microchannel: Effect of direct current‐dielectrophoretic force
Author(s) -
Ai Ye,
Joo Sang W.,
Jiang Yingtao,
Xuan Xiangchun,
Qian Shizhi
Publication year - 2009
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200800792
Subject(s) - microchannel , electric field , electrophoresis , dielectrophoresis , mechanics , particle (ecology) , physics , laplace's equation , current (fluid) , transient (computer programming) , classical mechanics , magnetosphere particle motion , charged particle , chemistry , boundary value problem , oceanography , chromatography , quantum mechanics , computer science , magnetic field , thermodynamics , geology , operating system , ion
Transient electrophoretic motion of a charged particle through a converging–diverging microchannel is studied by solving the coupled system of the Navier–Stokes equations for fluid flow and the Laplace equation for electrical field with an arbitrary Lagrangian–Eulerian finite‐element method. A spatially non‐uniform electric field is induced in the converging–diverging section, which gives rise to a direct current dielectrophoretic (DEP) force in addition to the electrostatic force acting on the charged particle. As a sequence, the symmetry of the particle velocity and trajectory with respect to the throat is broken. We demonstrate that the predicted particle trajectory shifts due to DEP show quantitative agreements with the existing experimental data. Although converging–diverging microchannels can be used for super fast electrophoresis due to the enhancement of the local electric field, it is shown that large particles may be blocked due to the induced DEP force, which thus must be taken into account in the study of electrophoresis in microfluidic devices where non‐uniform electric fields are present.