Facile Fabrication of Highly Sensitive Flexible Humidity Sensors by Laser Induced Graphene.

In this paper, a facile method for the preparation of highly sensitive humidity sensor is studied. The laser induced graphene (LIG) is used as electrodes. Polyimide (PI) film is used as both the substrate and humidity sensing material of the sensor. PI film is scanned by a picosecond infrared laser with controlled laser power and frequency to induce porous graphene electrodes. The micromorphology of the blank PI film and the PI between electrodes are visualized by the scanning electron microscope, showing that the number of pore cracks on the surface of polyimide between the LIG electrodes increased significantly compared with that of blank PI film, which enhance the ionic conductivity of PI, thus increasing the sensitivity of the sensor. This work allows rapid and low-cost mass production of highly sensitive humidity sensors for applications such as smart agriculture and healthcare monitoring.