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Phys. Rev. E 69, 051402 (2004) [6 pages]

Electrokinetic behavior of two touching inhomogeneous biological cells and colloidal particles: Effects of multipolar interactions

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J. P. Huang
Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong and Biophysics and Statistical Mechanics Group, Laboratory of Computational Engineering, Helsinki University of Technology, P.O. Box 9203, Helsinki FIN-02015 HUT, Finland

Mikko Karttunen
Biophysics and Statistical Mechanics Group, Laboratory of Computational Engineering, Helsinki University of Technology, P.O. Box 9203, Helsinki FIN-02015 HUT, Finland

K. W. Yu and L. Dong
Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong

G. Q. Gu
Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong and College of Information Science and Technology, East China Normal University, Shanghai 200 062, China

Received 7 November 2003; published 25 May 2004

We present a theory to investigate electrokinetic behavior, namely, electrorotation and dielectrophoresis under alternating current (ac) applied fields for a pair of touching inhomogeneous colloidal particles and biological cells. These inhomogeneous particles are treated as graded ones with physically motivated model dielectric and conductivity profiles. The mutual polarization interaction between the particles yields a change in their respective dipole moments, and hence in the ac electrokinetic spectra. The multipolar interactions between polarized particles are accurately captured by the multiple images method. In the point-dipole limit, our theory reproduces the known results. We find that the multipolar interactions as well as the spatial fluctuations inside the particles can affect the ac electrokinetic spectra significantly.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevE.69.051402
DOI:
10.1103/PhysRevE.69.051402
PACS:
82.70.−y, 77.22.Gm, 77.84.Lf