An analysis of induced pressure fields in electroosmotic flows through microchannels

Yonghao Zhang, X.J. Gu, Robert W. Barber, David Emerson

Research output: Contribution to journalArticle

34 Citations (Scopus)

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.
LanguageEnglish
Pages670-678
Number of pages8
JournalJournal of Colloid and Interface Science
Volume275
Issue number2
DOIs
Publication statusPublished - 2004

Fingerprint

Microchannels
Pressure gradient
Microfluidics
Capillary electrophoresis
Chromatography
Pressure distribution
Electric fields
Fluids
Computer simulation

Keywords

  • electroosmotic flow
  • microchannel
  • boundary conditions
  • creeping flow
  • mechanical engineering

Cite this

Zhang, Yonghao ; Gu, X.J. ; Barber, Robert W. ; Emerson, David. / An analysis of induced pressure fields in electroosmotic flows through microchannels. In: Journal of Colloid and Interface Science. 2004 ; Vol. 275, No. 2. pp. 670-678.
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An analysis of induced pressure fields in electroosmotic flows through microchannels. / Zhang, Yonghao; Gu, X.J.; Barber, Robert W.; Emerson, David.

In: Journal of Colloid and Interface Science, Vol. 275, No. 2, 2004, p. 670-678.

Research output: Contribution to journalArticle

TY - JOUR

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N2 - 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.

AB - 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.

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