Ultrasensitive paper-based polyaniline/graphene composite strain sensor for sign language expression

We report a facile, low cost and readily scalable method for the fabrication of a flexible paper-based strain sensor. Approaches of pen-writing, paper-transferring and elastomer-packaging were exploited to build a strain sensor with layered structures consisting of the graphene mesh and conductive polyaniline. The normalized conductivity change (ΔG/G0) and gauge factor could reach as high as 747 and 1.1×104, respectively. The mechanism of ultra-high conductivity change was attributed to the formation of micro-disconnection and micro-cracking in the layered structure deduced by Raman imaging and a simulation based on equivalent resistor networks. As a proof of the concept, the strain devices were finally exploited in sign language recognition. Our work demonstrated a new strategy to create ultra-high sensitive communication devices for people with speech and hearing impairment.