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Updated: Jul 23, 2025
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Patterning of Microorganisms and Microparticles through Sequential Capillarity-assisted Assembly
Published on: November 4, 2021
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Island hopping of active colloids
Venkata Manikantha Sai Ganesh Tanuku1, Peter Vogel1, Thomas Palberg1
1Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany. vtanuku@uni-mainz.de.
Soft Matter
|July 11, 2023
Summary
Self-propelled Janus particles (JP) navigate obstacles by abruptly reorienting upon collision with passive particle islands. This behavior mimics run-and-tumble swimmers, offering insights into active particle dynamics.
Area of Science:
- Soft matter physics
- Colloidal science
- Active matter physics
Background:
- Individual active particles like active Brownian particles (ABP) and run-and-tumble (RT) swimmers have well-defined motion patterns.
- The interaction of these active particles with obstacles is a critical, yet underexplored, research area.
Purpose of the Study:
- To investigate the 2D motion of Janus particles (JP) interacting with obstacles formed by passive colloids.
- To elucidate the mechanisms behind JP reorientation when encountering particle clusters.
Main Methods:
- Utilizing AC electric fields to actuate silica-gold Janus particles (JP) in a suspension of smaller passive silica particles.
- Observing JP movement through passive colloid aggregates, termed 'islands,' driven by electrohydrodynamic (EHD) flows.
Main Results:
- JP exhibit straight-line motion in open areas and undergo abrupt reorientations upon colliding with particle islands.
- Scattering events are attributed to the coupled effects of EHD flows, JP self-propulsion, and local torques.
- The resulting trajectories of JP closely resemble the run-and-tumble (RT) motion characteristic of biological microswimmers.
Conclusions:
- The study reveals that Janus particles interacting with colloidal islands display complex trajectories.
- The observed scattering mechanism provides a physical model for active particle navigation in structured environments.
- This research bridges the gap between synthetic active matter and biological microswimmer dynamics.
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