Peak compression and resolution for electrophoretic separations in diverging microchannels

David Ross, Cornelius F. Ivory, Laurie E. Locascio, Kevin E. Van Cott

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


We report the results of experiments and simulations on electrokinetic flow in diverging microchannels (with cross-sectional area that increases with distance along the channel). Because of conservation of mass and charge, the velocity of an analyte in the channel decreases as the channel cross-section increases. Consequently, the leading edge of a band of sample moves more slowly than the trailing edge and the sample band is compressed. Sample peak widths, rather than increasing diffusively with time, can then be controlled by the geometry of the channel and can even be made to decrease with time. We consider the possibility of using this peak compression effect to improve the resolution of electrophoretic separations. Our results indicate that for typical separations that are dispersion limited, this peak compression effect is more than offset by the decreased distance between peaks, and the separation resolution in diverging channels is worse than that found for straight channels at the same applied voltage. For separations in very short channels or at very high field strengths, however, when the separation efficiency is injection limited, the peak compression effect is dominant and diverging channels can then be used to achieve improved separation resolution.

Original languageEnglish (US)
Pages (from-to)3694-3704
Number of pages11
Issue number21-22
StatePublished - Nov 2004
Externally publishedYes


  • Electrokinetic flow
  • Microchannels
  • Miniaturization

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry


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