Sunlight‐Reduced Graphene Oxides as Sensitive Moisture Sensors for Smart Device Design

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.