▎ 摘　　要

Here, a facile fabrication of graphene-based humidity sensors is reported for smart device design. Focused sunlight photoreduction of graphene oxide (GO) helps to remove most of the oxygen-containing groups on GO sheets, which not only recovers their conductivity but also leads to the formation of a highly porous nanostructure, enabling the manufacture of versatile humidity-sensing smart devices, such as moisture controllers, humidity detector robots, and even a novel electronic harmonica, through a very simple technique. As an uncomplicated and chemical-free method, focused sunlight photoreduction of GO provides an avenue to produce versatile sensing devices for the development of smart devices.