Highly sensitive and stretchable graphene-silicone rubber composites for strain sensing

Flexible strain sensors made by conductive elastomer composites have attracted increasing attention. In this paper, the electromechanical properties of graphene-silicone rubber nanocomposites are studied systematically. First, the conductive nanocomposites composed of graphene and silicone rubber are prepared by means of co-coagulation, which shows a lower percolation threshold with 1.87 wt% (0.94 vol%). Second, the rubber nanocomposites with different graphene contents exhibit a very high strain sensitivity (gauge factor > 143) and a larger strain sensing range (>170%), also, the good recoverability and reproducibility have been found during the loading-unloading cycle. Finally, the analytical model based on the connectivity of the graphene nanosheets and the viscoelasticity of the rubber matrix is developed to describe the electromechanical properties and explain the 'shoulder peak' phenomenon, also a typical application example about monitoring the operate state of the rubber seal is given.