An unexpected particle oscillation for electrophoresis in viscoelastic fluids through a microchannel constriction |
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| Authors: | Xinyu Lu Saurin Patel Meng Zhang Sang Woo Joo Shizhi Qian Amod Ogale Xiangchun Xuan |
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| Institution: | 1.Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634-0921, USA;2.Department of Chemical and Biomolecular Engineering, and Center for Advanced Engineering Fibers and Films, Clemson University, Clemson, South Carolina 29634-0909, USA;3.School of Mechanical Engineering, Yeungnam University, Gyongsan 712-719, South Korea;4.Institute of Micro/Nanotechnology, Old Dominion University, Norfolk, Virginia 23529, USA |
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| Abstract: | Electrophoresis plays an important role in many applications, which, however, has so far been extensively studied in Newtonian fluids only. This work presents the first experimental investigation of particle electrophoresis in viscoelastic polyethylene oxide (PEO) solutions through a microchannel constriction under pure DC electric fields. An oscillatory particle motion is observed in the constriction region, which is distinctly different from the particle behavior in a polymer-free Newtonian fluid. This stream-wise particle oscillation continues until a sufficient number of particles form a chain to pass through the constriction completely. It is speculated that such an unexpected particle oscillating phenomenon is a consequence of the competition between electrokinetic force and viscoelastic force induced in the constriction. The electric field magnitude, particle size, and PEO concentration are all found to positively affect this viscoelasticity-related particle oscillation due to their respective influences on the two forces. |
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