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Updated: Mar 22, 2026
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An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
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Emergent ultra-long-range interactions between active particles in hybrid active-inactive systems
Joshua P Steimel1, Juan L Aragones1, Helen Hu1
1Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
Summary
Active spinning particles create ultra-long-range attraction in passive colloid mixtures. This emergent interaction, mediated by material elasticity, offers new possibilities for synthetic active soft materials.
Area of Science:
- Soft Matter Physics
- Active Matter Systems
- Colloidal Science
Background:
- Particle interactions dictate system behavior.
- Controlling interaction range and magnitude is a long-standing challenge.
- Active particles can form out-of-equilibrium cooperative states like flocking.
Purpose of the Study:
- Investigate effective interactions in active and passive colloid mixtures.
- Explore emergent interactions inspired by biological systems.
- Understand the role of elasticity in mediating active particle interactions.
Main Methods:
- Studied 2D colloidal monolayers with passive colloids and a small fraction of active ferromagnetic colloids.
- Analyzed systems with varying spinning protocols for active particles.
- Investigated the influence of actuation timescale on particle interactions.
Main Results:
- Observed an emergent ultra-long-range attractive interaction.
- This attraction is induced by active particle spinning and mediated by passive medium elasticity.
- Interaction appearance is dependent on the spinning protocol and requires a minimum actuation timescale.
Conclusions:
- Active particles can induce long-range interactions in elastic media without chemical modifications.
- This mechanism may be relevant for biological systems.
- Potential applications in developing synthetic active soft materials.
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