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Effect of direct current dielectrophoresis on the trajectory of a non‐conducting colloidal sphere in a bent pore
Author(s) -
House Dustin L.,
Luo Haoxiang
Publication year - 2011
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.201100323
Subject(s) - dielectrophoresis , mechanics , particle (ecology) , electrokinetic phenomena , electric field , magnetosphere particle motion , maxwell stress tensor , finite element method , physics , classical mechanics , dipole , point particle , materials science , cauchy stress tensor , nanotechnology , magnetic field , oceanography , quantum mechanics , thermodynamics , geology
Dielectrophoresis has shown a wide range of applications in microfluidic devices. Force approximations utilizing the point‐dipole method in dielectrophoresis have provided convenient predictions for particle motion by neglecting interactions between the particle and its surrounding electric and flow fields. The validity of this approach, however, is unclear when the particle size is comparable to the characteristic length of the channel and when the particle is in close proximity to the channel wall. To address this issue, we apply an accurate numerical approach based on the boundary‐element method (BEM) to solve the coupled electric field, flow, and particle motion. This method can handle much closer particle–wall distances than the other numerical approaches such as the finite‐element method. Using the BEM and integrating the Maxwell stress tensor, we simulate an electrokinetic, spherical particle moving within a bent cylindrical pore to investigate how the dielectrophoretic force affects the particle's trajectory. In the simulation, both the particle and the channel wall are non‐conducting, and the electric double layers adjacent to the solid surfaces are assumed to be thin with respect to the particle radius and particle–wall gap. The results show that as the particle comes close to the wall, its finite size has an increasingly important effect on its own transient motion and the point‐dipole approximation may lead to significant error.