Characterization of piezoresistive properties of graphene-supported polymer coating for strain sensor applications

An optically transparent nanographite coating has been developed on a poly-methyl methacrylate (PMMA) substrates. The adhesion to the PMMA surface combined with the shear stress allowed an uniform and continuous spreading of the graphite nanocrystals on the substrate surface with formation of a very uniform graphene multilayer coating. This coating is characterized by high piezoresitivity and it is suitable to work as sensible and reliable local strain sensor. Its piezoresistive features have been characterized by bending tests yielding a gauge factor (GF) which is of the order of 50. The structural and strain properties of the compound were studied under stress by infra-red thermography (IRT) and micro-Raman spectroscopy. The strain strength has been estimated as a function of the bending load. The electrical transport was investigated as a function of the applied stress. Features are consistent with an intergrain electrical transport mechanism among graphene platelets.