▎ 摘　　要

We reported here a facile, green, and simple method to fabricate moistureresponsive graphene actuators by moderate flash reduction of graphene oxides (GO) films. Due to the limited light transparency and thermal relaxation, the oxygen containing groups (OCGs) on the GO sheets could be selectively removed from the radiation side, forming a photoreduction gradient along the lateral direction of the GO film. In this manner, we obtained a reduced GO (RGO)/GO bilayer film. The RGO/GO film can bend to the RGO side when exposed to moisture because RGO and GO layers show different absorption capabilities of water molecules. Taking advantage of this controllable deformation, we fabricated moisture-responsive actuators including a crawler and claw robots. (C) 2017 Optical Society of America.