Visible Light Actuated Efficient Exclusion Between Plasmonic Ag/AgCl Micromotors and Passive Beads

Abstract

Insight is provided into the collective behavior of visible-light photochemically driven plasmonic Ag/AgCl Janus particles surrounded by passive polystyrene (PS) beads. The active diffusion of single Janus particles and their clusters (small: consisting of two or three Janus particles and large: consisting of more than ten Janus particles), and their interaction with passive PS beads, are analyzed experimentally and in simulations. The diffusivity of active Janus particles, and thus the exclusive effect to passive PS beads, can be regulated by the number of single Janus particles in the cluster. On the simulation side, the Langevin equations of motion for self-propelled Janus particles and diffusing passive PS beads are numerically solved using Molecular-Dynamics simulations. The complex interactions of both subsystems, including elastic core-to-core interactions, short-range attraction, and effective repulsion due to light-induced chemical reactions are considered. This complex mixed system not only provides insight to the interactive effect between active visible light-driven self-propelled micromotors and passive beads, but also offers promise for implications in light-controlled propulsion transport and chemical sensing.

Keywords: active Janus particles; exclusion interaction; passive beads; visible light-driven micromotors.