Highly Conductive Silicone Elastomers via Environment-Friendly Swelling and In Situ Synthesis of Silver Nanoparticles

Flexible and stretchable conductors are crucial components for next-generation flexible devices. Wrinkled structures often have been created on such conductors by depositing conductive materials on the pre-stretched or organic solvent swollen samples. Herein, water swelling is first proposed to generate the wrinkled structures on silicone elastomers. By immersing silicone/sugar hybrid in water, a significant amount of swelling occurs as a result of osmosis and capillary interactions with the sugar and silicone matrix. Considering the drastic swelling effect and controllable swelling ratio, water swelling is used to replace the conventional pre-stretching and organic solvent swelling to fabricate stretchable conductors. In situ growing of silver nanoparticles (AgNPs) is carried out on the swollen silicone elastomers. Wrinkled conductive silicone elastomers are successfully constructed after removing the residual water. The conductive elastomer has a sheet resistance of less than 1 Ω sq-1 at zero strain and also shows high sensitivity when subjected to external deformation up to 100% strain. The silicone/sugar composite also possesses good 3D printability with the desired shear-thinning property. Human motion detection is demonstrated using the 3D printed sensors. This work provides a facile and environment-friendly strategy to fabricate superior flexible and stretchable sensing devices.