Light-Programmable Assemblies of Isotropic Micromotors

“Life-like”nonequilibrium assemblies are of increasing significance,but suffering from limited steerability as they are generally based on micro/nanomotors with inherent asymmetry in chemical composition or geometry,of which the vigorous random Brownian rotations disturb the local interactions.Here,we demonstrate that isotropic photocatalytic micromotors,due to the persistent phoretic flow from the lluminated to shadowed side rrespective of their Brownian rotations,experience lightprogrammable local interactions(reversibly from atraction to repulsion and/or alignment)depending on the direction of the incident lights.Thus,they can be organized into a variety of tunable nonequilibrium assemblies,such as apolar solids(i.e.,immobile colloidal crystal),polar liquids(ie.,phototactic colloidal stream),and polar solids(i.e.,phototactic colloidal crystal),which can further be“cut”into a predesigned pattern by utilizing the switching motor-motor interactions at superimposedlight edges.This work facilitates the development of active matters and motile functional microdevices.