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Updated: Aug 8, 2025
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Published on: May 20, 2014
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The interplay between chemo-phoretic interactions and crowding in active colloids
Federico Fadda1, Daniel A Matoz-Fernandez2, René van Roij3
1Institute of Physics, University of Amsterdam, 1098 XH Amsterdam, The Netherlands. fede.fadda1110@gmail.com.
Soft Matter
|March 1, 2023
Summary
Crowding and chemical signaling influence how active colloids form structures. New research reveals a novel phase-separated state emerging from competition between diffusiophoretic interactions and motility.
Area of Science:
- Physics
- Chemistry
- Biophysics
Background:
- Motile microorganisms use chemical signals for long-range interactions via self-generated gradients.
- The combined effects of crowding and chemotaxis on collective behavior are not well understood.
Purpose of the Study:
- Investigate how packing fraction influences non-equilibrium structure formation in active colloids.
- Model chemically active particles using a monolayer of diffusiophoretic self-propelled colloids.
Main Methods:
- Utilize Brownian dynamics simulations.
- Analyze dynamical steady-states across varying packing fractions and motility levels.
- Focus on attractive positional and repulsive orientational interactions induced by chemical fields.
Main Results:
- Observed collapsed, active gas, and dynamical clustering states at low packing fractions.
- Identified a new phase-separated state emerging at moderate activities and a range of packing fractions.
- Phase separation arises from the interplay between diffusiophoretic interactions and motility.
Conclusions:
- The fraction of particles in the largest cluster can serve as an order parameter.
- This order parameter effectively captures transitions between active gas, dynamical clustering, and phase-separated states.
- The study elucidates the complex collective behaviors driven by chemical signaling and crowding in active matter.
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