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Force Generation in Confined Active Fluids: The Role of Microstructure
Shuvojit Paul1, Ashreya Jayaram2, N Narinder1
1Fachbereich Physik, Universität Konstanz, 78464 Konstanz, Germany.
Physical Review Letters
|August 12, 2022
Summary
We measured the force active particles exert on a probe near a wall. This force directly relates to particle density, confirming a general relationship between active particle microstructure and transmitted forces.
Area of Science:
- Soft matter physics
- Active matter systems
- Statistical mechanics
Background:
- Active matter systems, composed of self-propelled units, exhibit unique emergent behaviors.
- Understanding force transmission in these systems is crucial for applications in micro-robotics and biological systems.
- The influence of boundaries, like walls, on active particle interactions and force generation is not fully understood.
Purpose of the Study:
- To experimentally quantify the force exerted by active particles on a passive probe as a function of probe-wall distance.
- To investigate the relationship between this force and the local averaged density distribution of active particles.
- To validate findings with a minimal numerical model and establish a general relationship.
Main Methods:
- Experimental setup involving a bath of active particles and a passive probe near a wall.
- Measurement of forces exerted on the probe at varying distances from the wall.
- Quantification of the averaged density distribution of active particles around the probe.
- Comparison with a minimal numerical model.
Main Results:
- The force exerted by active particles on the probe was successfully measured.
- A direct relationship, up to a factor, was found between the transmitted force and the averaged density distribution of active particles.
- Experimental results showed excellent agreement with the minimal numerical model.
Conclusions:
- A general and system-independent relationship exists between the microstructure of active particles and transmitted forces.
- The active stress framework effectively describes the force transmission in this system.
- The study provides a fundamental understanding of force-mediated interactions in active matter systems near boundaries.
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