Clustering and emergent hyperuniformity by breaking microswimmer shape and actuation symmetries

TL;DR

This study reveals how breaking shape and actuation symmetries in microswimmers induces stable clustering and hyperuniform structures through hydrodynamic interactions, advancing understanding of active matter self-organization.

Contribution

It introduces a new mechanism for hierarchical self-organization in active matter by breaking symmetries in microswimmer design, leading to hyperuniform structures.

Findings

Breaking symmetries enables stable cluster formation.

Cluster-sourced flows lead to hyperuniform structures.

Hydrodynamic interactions drive long-range order.

Abstract

Hydrodynamic interactions driven by particle activity are ubiquitous in active colloidal systems. Although these interactions are strongly influenced by the interfacial actuation mechanism and geometry of the swimming particles, theoretical understanding of how these microscopic design parameters govern collective dynamics remains limited. Here, we investigate the collective dynamics of oblate spheroidal microswimmers. Using an approximate kinetic theory and corroborating boundary element method calculations, we demonstrate that breaking symmetries in both particle shape and interfacial actuation enables the emergence of dynamically stable immotile n-particle clusters. At larger scales, the clustering process drives the system into a dynamically arrested absorbing state characterized by disordered class I hyperuniform structures. Our analysis highlights the essential role of cluster-sourced long-range flows in establishing this long-range order. Overall, our findings reveal a robust, purely hydrodynamic mechanism for hierarchical self-organization in active matter systems, providing a novel strategy for engineering multifunctional hyperuniform materials.