3D-Printed Graphene/Polydimethylsiloxane Composites for Stretchable and Strain-Insensitive Temperature Sensors.

Materials possessing exceptional temperature sensitivity and high stretchability are of importance for real-time temperature monitoring on three-dimensional components with complex geometries, when operating under various external deformation modes. Herein, we develop a stretchable temperature sensor consisting of cellular graphene/polydimethylsiloxane composite. The first of its kind, graphene-based polymer composites with desired microstructures are produced through a direct 3D ink-writing technique. The resultant composites possess long-range-ordered and precisely controlled cellular structure. Temperature-sensing properties of three cellular structures, including grid, triangular, and hexagonal porous structures are studied. It is found that all three cellular composites present more stable sensitivities than solid composites under external strains because of the fine porous structure that can effectively share the external strain, and the composites with a grid structure delivered particularly a stable sensing performance, showing only ∼15% sensitivity decrease at a large tensile strain of 20%. Taking full advantage of the composites with a grid structure in terms of sensitivity, durability, and stability, practical applications of the composite are demonstrated to monitor the cooling process of a heated tube and measure skin temperature accompanying an arbitrary wristwork.