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Artificial Chemotaxis of Self-Phoretic Active Colloids: Collective Behavior
1Technische Universität Berlin , Institute of Theoretical Physics , Hardenbergstrasse 36 , D-10623 Berlin , Germany.
Accounts of Chemical Research
|October 23, 2018
Summary
Artificial microswimmers use diffusiophoresis to navigate chemical gradients, mimicking natural chemotaxis. This study explores their collective behaviors, revealing dynamic clustering and phase separation driven by self-generated chemical fields.
Area of Science:
- Colloid Science
- Soft Matter Physics
- Chemical Engineering
Background:
- Microorganisms navigate chemical gradients via chemotaxis for survival.
- Artificial microswimmers can replicate this using diffusiophoresis, a physical process driven by chemical fields.
Purpose of the Study:
- To investigate the chemotaxis of self-phoretic active colloids.
- To understand emergent collective behaviors arising from self-generated chemical fields and inter-particle interactions.
Main Methods:
- Formulation of Langevin equations for active colloids' position and orientation.
- Modeling of translational and rotational diffusiophoresis, including chemical field screening for dense packings.
- Construction of state diagrams based on diffusiophoretic parameters to map collective behaviors.
Main Results:
- Identified diverse collective states including gas-like, dynamic clustering (states 1 and 2), and collapsed states.
- Demonstrated dynamic clustering driven by a balance of attraction and repulsion, contrasting with static motility-induced phase separation.
- Characterized different collapsed states, including a full chemotactic collapse and its transition to oscillating and static clouds under repulsion.
Conclusions:
- The study provides a theoretical framework for understanding active colloid behavior driven by diffusiophoresis.
- The developed model connects to the Keller-Segel model for microorganisms' chemotaxis.
- The theory is extensible to mixtures and includes dipolar corrections for Janus colloids.
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