Light actuated swarming and breathing-like motion of graphene oxide colloidal particles

Abstract

Synthetic microparticles that can be propelled under light stimulus and generate collective behaviors via interaction among these particles may lead to applications in numerous fields. Here we show that aqueous graphene oxide (GO) particles can move autonomously to a light source. These self-propelled multilayer GO particles swarm but periodically “stop to take a breath” under continuous light stimulus. UV light causes a movement velocity of approximately 25 μm s−1 and oscillating frequency of approximately two times per minute for multilayer GO particles. Light with a wavelength longer than green light causes neither locomotion nor oscillation. Only multilayer GO particles exhibit the oscillating behavior. This unusual oscillating mode suggests that multilayer GO particles may undergo non-equilibrium dynamic processes in their light-actuated collective motion.