Ultrasensitive Strain Gauges Enabled By Graphene-Stabilized Silicone Emulsions

Here, an approach is presented to incorporate graphene nanosheets into a silicone rubber matrix via solid stabilization of oil-in-water emulsions. These emulsions can be cured into discrete, graphene-coated silicone balls or continuous, elastomeric films by controlling the degree of coalescence. The electromechanical properties of the resulting composites as a function of interdiffusion time and graphene loading level are characterized. With conductivities approaching 1 S m(-1), elongation to break up to 160%, and a gauge factor of approximate to 20 in the low-strain linear regime, small strains such as pulse can be accurately measured. At higher strains, the electromechanical response exhibits a robust exponential dependence, allowing accurate readout for higher strain movements such as chest motion and joint bending. The exponential gauge factor is found to be approximate to 20, independent of loading level and valid up to 80% strain; this consistent performance is due to the emulsion-templated microstructure of the composites. The robust behavior may facilitate high-strain sensing in the nonlinear regime using nanocomposites, where relative resistance change values in excess of 10(7) enable highly accurate bodily motion monitoring.