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Issue 5, 2014
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Acoustic focusing with engineered node locations for high-performance microfluidic particle separation

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Abstract

Acoustofluidic devices for manipulating microparticles in fluids are appealing for biological sample processing due to their gentle and high-speed capability of sorting cell-scale objects. Such devices are generally limited to moving particles toward locations at integer fractions of the fluid channel width (1/2, 1/4, 1/6, etc.). In this work, we introduce a unique approach to acoustophoretic device design that overcomes this constraint, allowing us to design the particle focusing location anywhere within the microchannel. This is achieved by fabricating a second fluid channel in parallel with the sample channel, separated from it by a thin silicon wall. The fluids in both channels participate to create the ultrasound resonance, while only one channel processes the sample, thus de-coupling the fluidic and acoustic boundaries. The wall placement and the relative widths of the adjacent channels define the particle focusing location. We investigate the operating characteristics of a range of these devices to determine the configurations that enable effective particle focusing and separation. The results show that a sufficiently thin wall negligibly affects focusing efficiency and location compared to a single channel without a wall, validating the success of this design approach without compromising separation performance. Using these principles to design and fabricate an optimized device configuration, we demonstrate high-efficiency focusing of microspheres, as well as separation of cell-free viruses from mammalian cells. These “transparent wall” acoustic devices are capable of over 90% extraction efficiency with 10 μm microspheres at 450 μL min−1, and of separating cells (98% purity), from viral particles (70% purity) at 100 μL min−1.

Graphical abstract: Acoustic focusing with engineered node locations for high-performance microfluidic particle separation

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Publication details

The article was received on 07 Jan 2014, accepted on 10 Jan 2014 and first published on 13 Jan 2014


Article type: Paper
DOI: 10.1039/C4AN00034J
Citation: Analyst, 2014,139, 1192-1200
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    Acoustic focusing with engineered node locations for high-performance microfluidic particle separation

    E. J. Fong, A. C. Johnston, T. Notton, S. Jung, K. A. Rose, L. S. Weinberger and M. Shusteff, Analyst, 2014, 139, 1192
    DOI: 10.1039/C4AN00034J

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