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An analysis of induced pressure fields in electroosmotic flows through microchannels

Zhang, Yonghao and Gu, X.J. and Barber, Robert W. and Emerson, David (2004) An analysis of induced pressure fields in electroosmotic flows through microchannels. Journal of Colloid and Interface Science, 275 (2). pp. 670-678. ISSN 0021-9797

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    Abstract

    Induced pressure gradients are found to cause band-broadening effects which are important to the performance of microfluidic devices, such as capillary electrophoresis and capillary chromatography. An improved understanding of the underlying mechanisms causing an induced pressure gradient in electroosmotic flows is presented. The analysis shows that the induced pressure distribution is the key to understanding the experimentally observed phenomena of leakage flows. A novel way of determining the static pressures at the inlet and outlet of microchannels is also presented that takes account of the pressure losses due to flow contraction and expansion. These commonly neglected pressure losses at the channel entrance and outlet are shown to be important in accurately describing the flow. The important parameters that define the effect of induced pressure on the flows are discussed, which may facilitate the design of improved microfluidic devices. The present model clearly identifies the mechanism behind the experimentally observed leakage flows, which is further confirmed by numerical simulations. Not only can the leakage flow occur from the electric-field-free side channel to the main channel, but also the fluid in the main channel can be attracted into the side channel by the induced pressure gradient.

    Item type: Article
    ID code: 5077
    Keywords: electroosmotic flow, microchannel, boundary conditions, creeping flow, mechanical engineering, Mechanical engineering and machinery, Biomaterials, Surfaces, Coatings and Films, Colloid and Surface Chemistry, Electronic, Optical and Magnetic Materials
    Subjects: Technology > Mechanical engineering and machinery
    Department: Faculty of Engineering > Mechanical and Aerospace Engineering
    Related URLs:
      Depositing user: Strathprints Administrator
      Date Deposited: 07 Jan 2008
      Last modified: 20 Jun 2014 05:58
      URI: http://strathprints.strath.ac.uk/id/eprint/5077

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