Transparent graphene films with a tunable piezoresistive response

We demonstrate a graphene-coated polymer film as a transparent piezoresistive strain sensor. Strain sensitivity was tuned by controlling the thickness and density of the graphene layer as well as the adhesion force between graphene and the substrate. Chemically reducing the graphene oxide, thereby maximizing its adhesion to the substrate, while minimizing the coating density and thickness resulted in excellent transparency and high gauge factors. The fabrication method presented allows design optimization of transparent, high-performance, and sensitivity-tunable piezoresistive sensors, which can make inroads into such applications as wide-area strain sensors, self-sensing flexible electronics, and intelligent structural health monitoring.