Light-switchable propulsion of active particles with reversible interactions

Abstract

Active systems such as microorganisms and self-propelled particles show a plethora of collective phenomena, including swarming, clustering, and phase separation. Control over the propulsion direction and switchability of the interactions between the individual self-propelled units may open new avenues in designing of materials from within. Here, we present a self-propelled particle system, consisting of half-gold coated titania (${\mathrm{TiO}}_2$) particles, in which we can fast and on-demand reverse the propulsion direction, by exploiting the different photocatalytic activities on both sides. We demonstrate that the reversal in propulsion direction changes the nature of the hydrodynamic interaction from attractive to repulsive and can drive the particle assemblies to undergo both fusion and fission transitions. Moreover, we show these active colloids can act as nucleation sites, and switch rapidly the interactions between active and passive particles, leading to reconfigurable assembly and disassembly. Our experiments are qualitatively described by a minimal hydrodynamic model.

arXiv comment28 pages, 4 figures

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• Direction reversing active Brownian particle in a harmonic potential
• Thermodynamics of active matter: Tracking dissipation across scales
• Collective self-optimization of communicating active particles
• A Brownian cyclic engine operating in a viscoelastic active suspension
• Transient coarsening and the motility of optically heated Janus colloids in a binary liquid mixture
• Discovering dynamic laws from observations: the case of self-propelled, interacting colloids
• Universal reshaping of arrested colloidal gels via active doping
• Dynamics of switching processes: general results and applications to intermittent active motion
• Electrophoresis of metal-dielectric Janus particles with dipolar director symmetry in nematic liquid crystals
• Cluster dynamics in macroscopic photoactive particles
• Relaxation to steady states of a binary liquid mixture around an optically heated colloid
• Active colloid with externally induced periodic bipolar motility and its cooperative motion
• Temperature switchable self-propulsion activity of liquid crystalline microdroplets
• Light-Activated Self-thermophoretic Janus Nanopropellers
• Shape anisotropy governs organization of active rods: Swarming, turbulence, flocking, and jamming
• A Data-Driven Statistical Description for the Hydrodynamics of Active Matter
• Programmable Persistent Random Walks in Active Brownian Particles Govern Emergent Dynamics
• Collective dynamics of macroscopic photoactive matter under alternating excitation patterns