We employ extensive computer simulations to study the flow behavior of spherical, nanoscale colloids in a viscoelastic solvent under Poiseuille flow. The systems are confined in a slit-like microfluidic channel, and viscoelasticity is introduced explicitly through the inclusion of polymer chains on the same length scale as the dispersed solute particles. We systematically study the effects of flow strength and polymer concentration, and identify a regime in which the colloids migrate to the centerline of the microchannel, expelling the polymer chains to the sides. This behavior was recently identified in experiments, but a detailed understanding of the underlying physics was lacking. To this end, we provide a detailed analysis of this phenomenon and discuss ways to maximize its effectiveness. The focusing mechanism can be exploited to separate and capture particles at the sub-micrometer scale using simple microfluidic devices, which is a crucial task for many biomedical applications, such as cell counting and genomic mapping.
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7 March 2014
Research Article|
March 06 2014
Flow-induced demixing of polymer-colloid mixtures in microfluidic channels
Arash Nikoubashman;
Arash Nikoubashman
Department of Chemical and Biological Engineering,
Princeton University
, Princeton, New Jersey 08544, USA
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Nathan A. Mahynski;
Nathan A. Mahynski
Department of Chemical and Biological Engineering,
Princeton University
, Princeton, New Jersey 08544, USA
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Amir H. Pirayandeh;
Amir H. Pirayandeh
Department of Chemical and Biological Engineering,
Princeton University
, Princeton, New Jersey 08544, USA
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Athanassios Z. Panagiotopoulos
Athanassios Z. Panagiotopoulos
a)
Department of Chemical and Biological Engineering,
Princeton University
, Princeton, New Jersey 08544, USA
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a)
Author to whom correspondence should be addressed. Electronic mail: azp@princeton.edu
J. Chem. Phys. 140, 094903 (2014)
Article history
Received:
December 05 2013
Accepted:
February 06 2014
Connected Content
A correction has been published:
Erratum: Flow-induced demixing of polymer-colloid mixtures in microfluidic channels [J. Chem. Phys. 140, 094903 (2014)]
Citation
Arash Nikoubashman, Nathan A. Mahynski, Amir H. Pirayandeh, Athanassios Z. Panagiotopoulos; Flow-induced demixing of polymer-colloid mixtures in microfluidic channels. J. Chem. Phys. 7 March 2014; 140 (9): 094903. https://doi.org/10.1063/1.4866762
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