Electromechanical strain sensing using polycarbonate-impregnated carbon nanotube–graphene nanoplatelet hybrid composite sheets

We report an experimental study on the electromechanical strain sensing ability of polycarbonate-impregnated hybrid sheets consisting of exfoliated graphite nanoplatelets, nanographene platelets, and multi-walled carbon nanotubes. The hybrid sheets were fabricated through surfactant-aided carbon nanomaterial dispersion followed by vacuum-induced filtration. The inherently porous sheets were impregnated with polycarbonate by infiltrating a polycarbonate–chloroform solution through the sheets. SEM analyses revealed that combining nanomaterials of various sizes and dimensions can serve as a means to control the porous network structure, which allows controlled polymer impregnation and tailored strain sensitivity. The wide-area strain sensing ability of the polymer-impregnated composite sheets was demonstrated by subjecting the composites with multiple electrodes to a flexural load and measuring the piezoresistivity in situ. The study demonstrated successful hybridization of 1D fiber-like and 2D platelet-like carbon nanomaterials into freestanding sheets with controlled nanostructure and properties, which can be used as preforms for easy-to-handle, high-carbon-content, multi-functional composite sheets.