Related Experiment Video
Updated: Jul 4, 2026
10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
Structure of colloidal gels during microchannel flow.
Jacinta C Conrad1, Jennifer A Lewis
1Frederick Seitz Materials Research Laboratory, Materials Science and Engineering Department, University of Illinois, Urbana, Illinois 61801, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|June 28, 2008
Summary
This study reveals how colloidal gels behave in microchannels. Under shear, gels form clusters that break apart, changing flow from pluglike to fluidlike.
Area of Science:
- Colloid and Surface Science
- Rheology
- Microfluidics
Background:
- Colloidal gels are complex fluids with applications in food, medicine, and materials science.
- Understanding their behavior under flow is crucial for process design and product development.
- Microfluidic devices offer a controlled environment to study these phenomena.
Purpose of the Study:
- To investigate the structure and flow dynamics of colloidal gels within microchannels.
- To correlate structural changes with macroscopic flow behavior under varying shear conditions.
Main Methods:
- Confocal microscopy was employed to visualize gel microstructure.
- Silica particles were modified with polyelectrolytes to induce gelation.
- Controlled shear flow was applied within microchannels.
Main Results:
- In quiescent state, the gel exhibited an isotropic and homogeneous structure.
- Under shear, dense clusters formed and yielded at intercluster boundaries.
- Network breakup was observed at high shear rates.
- Flow transitioned from pluglike at low pressures to fluidlike at high pressures.
Conclusions:
- Shear-induced structural changes, specifically cluster formation and network breakup, dictate the rheological properties of colloidal gels in microchannels.
- The observed transition in flow behavior is directly linked to the gel's response to applied stress.
Related Concept Videos
01:29The Colloidal State
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called the...
03:22Colloids
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible to the naked eye or can be seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a homogeneous mixture in which no settling occurs and in which the dissolved...
01:17Colloids and Suspensions
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles visible to the naked eye or seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. The suspended particles in a suspension settle out after some time of mixing. The separation of particles from a suspension is...