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Issue 16, 2012
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Lateral migration and focusing of colloidal particles and DNA molecules under viscoelastic flow

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Abstract

Much difficulty has been encountered in manipulating small-scale materials, such as submicron colloidal particles and macromolecules (e.g., DNA and proteins), in microfluidic devices since diffusion processes due to thermal (Brownian) motion become more pronounced with decreasing particle size. Here, we present a novel approach for the continuous focusing of such small-scale materials. First, we successfully focused fluorescent submicron polystyrene (PS) beads along equilibrium positions in microchannels through the addition of a small amount water-soluble polymer [500 ppm poly(ethylene oxide) (PEO)]. Lateral migration velocity significantly depends upon the viscoelastic effect (Weissenberg number: Wi) and the aspect ratio of particle size to channel height (a/h). Interestingly, focusing using viscoelastic flows was also observed for flexible DNA molecules (λ-DNA and T4-DNA), which have radii of gyration (Rg) of approximately 0.69 μm and 1.5 μm, respectively. This small-scale material manipulation using medium viscoelasticity will contribute to the design of nanoparticle separation and genomic mapping devices.

Graphical abstract: Lateral migration and focusing of colloidal particles and DNA molecules under viscoelastic flow

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Publication details

The article was received on 10 Feb 2012, accepted on 29 May 2012 and first published on 30 May 2012


Article type: Paper
DOI: 10.1039/C2LC40147A
Lab Chip, 2012,12, 2807-2814

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    Lateral migration and focusing of colloidal particles and DNA molecules under viscoelastic flow

    J. Young Kim , S. Won Ahn , S. Sik Lee and J. Min Kim, Lab Chip, 2012, 12, 2807
    DOI: 10.1039/C2LC40147A

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