Guiding self-assembly of active colloids by temporal modulation of activity

TL;DR

This study demonstrates how temporal modulation of activity in self-propelled colloids can control their self-organization into dynamic lattice structures, combining experiments and simulations to understand underlying mechanisms.

Contribution

It introduces a novel method of pattern control in active colloids through pulsating electric fields, advancing active matter manipulation techniques.

Findings

Colloids self-organize into square lattices with controllable lattice constants.

Dynamic lattices exhibit hysteresis under compression and expansion.

The mechanism is applicable to other active colloidal systems.

Abstract

Self-organization phenomena in ensembles of self-propelled particles open pathways to the synthesis of new dynamic states not accessible by traditional equilibrium processes. The challenge is to develop a set of principles that facilitate the control and manipulation of emergent active states. Here, we report that dielectric rolling colloids energized by a pulsating electric field self-organize into alternating square lattices with a lattice constant controlled by the parameters of the field. We combine experiments and simulations to examine spatiotemporal properties of the emergent collective patterns, and investigate the underlying dynamics of the self-organization.We reveal the resistance of the dynamic lattices to compression/expansion stresses leading to a hysteretic behavior of the lattice constant. The general mechanism of pattern synthesis and control in active ensembles via temporal modulation of activity can be applied to other active colloidal systems.