Direct flow visualization of colloidal gels in microfluidic channels

Mark T. Roberts, Ali Mohraz, Kenneth T. Christensen, Jennifer A. Lewis

Research output: Contribution to journalArticlepeer-review


The behavior of colloidal gels under pressure-driven flow in square microchannels is quantified by microscopic particle image velocimetry (μPTV) and compared to predictions of available rheological models. The gels consist of hydrophobically modified silica microspheres (Φ = 0.15-0.33) suspended in a refractive index-matched fluid along with fluorescent tracers to aid visualization. Measured velocity flow profiles show a transition from plug flow to more fluid-like behavior with increasing volumetric flow rate (Q) at all Φ. This transition is not captured by theoretical predictions of the flow profile based on the Herschel-Bulkley model. Rather, a model that accounts for gel breakup into a suspension of clusters at elevated shear rates by assuming a finite viscosity at infinite shear is needed to accurately predict the flow behavior of colloidal gels at large Q.

Original languageEnglish (US)
Pages (from-to)8726-8731
Number of pages6
Issue number17
StatePublished - Aug 14 2007

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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