Shape anisotropy governs organization of active rods: Swarming, turbulence, flocking, and jamming
arXiv:2605.02590 · doi:10.1126/science.ady7618
Abstract
Shape anisotropy of individual building blocks plays a crucial role in creating exotic structures and controlling phase behavior in equilibrium systems. We present a combined experimental and simulation study in which we used light-driven self-propelled rods to investigate when and how shape-induced alignment and steric and hydrodynamic interactions govern self-organization. Varying rod aspect ratio and area fraction causes the system to evolve from active Brownian motion to swarming, active turbulence, flocking, large clusters, and jamming. A state diagram summarizes emergent behaviors, and spatiotemporal analyses reveal distinct giant-number fluctuations across states. This minimal model offers insight into the self-organization of biological rodlike microswimmers, enabling the decoupling of physical from biological mechanisms. Our results provide design rules for programmable synthetic active materials and highlight parallels with bacterial swarms and other biological assemblies.
arXiv comment51 pages, 28 figures. Published in Science (9th April 2026)
References in corpus (22)
- Active Particles in Complex and Crowded Environments
- Motility-Induced Phase Separation
- Meso-scale turbulence in living fluids
- Long-lived Giant Number Fluctuations in a Swarming Granular Nematic
- Fluid dynamics and noise in bacterial cell-cell and cell-surface scattering
- Dynamic clustering in active colloidal suspensions with chemical signaling
- Hydrodynamics of self-propulsion near a boundary: predictions and accuracy of far-field approximations
- Non-equilibrium clustering of self-propelled rods
- Fluid Flows Created by Swimming Bacteria Drive Self-Organization in Confined Suspensions
- Swarming and swirling in self-propelled polar granular rods
- Large-scale collective properties of self-propelled rods
- Collective motion and nonequilibrium cluster formation in colonies of gliding bacteria
- Active Turbulence
- Self-Propelled Rods: Insights and Perspectives for Active Matter
- Hydrodynamics of self-propelled hard rods
- Sculpting vesicles with active particles: Less is more
- Swarm behavior of self-propelled rods and swimming flagella
- Long-range nematic order and anomalous fluctuations in suspensions of swimming filamentous bacteria
- Light-switchable propulsion of active particles with reversible interactions
- A particle-field representation unifies paradigms in active matter
- Active turbulence in microswimmer suspensions -- the role of active hydrodynamic stress and volume exclusion
- The 2024 Motile Active Matter Roadmap