Self-propelled Janus particles are artificial microscopic vehicles, or micromotors, that can perform complex tasks on a microscopic scale, suitable, e.g., for environmental applications, on-chip chemical information processing or in vivo drug delivery. Development of these smart devices requires a better understanding of how synthetic swimmers move in crowded and confined environments that mimic actual bio-systems. The active diffusion of Janus particles interacting with catalytically passive silica beads in narrow channels has been studied in numerical simulations [1] and experiments [2]. Active transport of Janus particles revealed a number of intriguing properties such as self- rectification and autonomous pumping in asymmetric channels [1], directional "locking" and channel "unclogging" [2] whereby a Janus swimmer is capable of transporting large clusters of passive particles [1, 2]. This effect can be used to manipulate colloidal transport in arrays of traps, e.g., to confine passive beads or extract them from the traps [3], by tuning the parameters of the active species. This has potential application in biology and medicine, e.g., to remove dead cells or undesired contaminants from biological systems by means of self- propelled nano-robots. Recently, visible light-driven Ag/AgCl-based spherical Janus micromotors have been demonstrated, which couple plasmonic light absorption with the photochemical decomposition of AgCl. These new Janus micromotors reveal high motility in pure water, with mean squared displacements (MSD) 100x higher than previously studied visible light-driven Janus micromotors, which was achieved by their design and suppression of the rotational diffusion. In presence of passive beads, the visible light-actuated exclusion effect between clusters of Janus motors and passive beads is demonstrated [5]. This mixed system with complex interactions offers promise for implications in light-controlled propulsion transport and chemical sensing.
Self-propelled Janus particles are artificial microscopic vehicles, or micromotors, that can perform complex tasks on a microscopic scale, suitable, e.g., for environmental applications, on-chip chemical information processing or in vivo drug delivery. Development of these smart devices requires a better understanding of how synthetic swimmers move in crowded and confined environments that mimic actual bio-systems. The active diffusion of Janus particles interacting with catalytically passive silica beads in narrow channels has been studied in numerical simulations [1] and experiments [2]. Active transport of Janus particles revealed a number of intriguing properties such as self- rectification and autonomous pumping in asymmetric channels [1], directional "locking" and channel "unclogging" [2] whereby a Janus swimmer is capable of transporting large clusters of passive particles [1, 2]. This effect can be used to manipulate colloidal transport in arrays of traps, e.g., to confine passive beads or extract them from the traps [3], by tuning the parameters of the active species. This has potential application in biology and medicine, e.g., to remove dead cells or undesired contaminants from biological systems by means of self- propelled nano-robots. Recently, visible light-driven Ag/AgCl-based spherical Janus micromotors have been demonstrated, which couple plasmonic light absorption with the photochemical decomposition of AgCl. These new Janus micromotors reveal high motility in pure water, with mean squared displacements (MSD) 100x higher than previously studied visible light-driven Janus micromotors, which was achieved by their design and suppression of the rotational diffusion. In presence of passive beads, the visible light-actuated exclusion effect between clusters of Janus motors and passive beads is demonstrated [5]. This mixed system with complex interactions offers promise for implications in light-controlled propulsion transport and chemical sensing.
