Self-Adhesive Elastic Conductive Ink with High Permeability and Low Diffusivity for Direct Printing of Universal...

Elastic conductive ink (ECI) can effectively balance the electromechanical properties of printed flexible electronics. It remains challenging to realize ECIs for direct printing on deformable porous substrates with complex textures, such as textiles, to form continuous and stable electrical paths. We engineered a self-adhesive ECI with high permeability and low diffusivity, achieving efficient electrode printing on a wide range of textiles with material and structure diversity. The ECI consists of a microphase separation-toughened elastomer (styrene-isoprene-styrene/ethyl vinyl acetate (SIS-EVA)) and a binary conductive filler. SIS-EVA provides a tough framework to protect silver flakes (AgFKs) and forms a ductile conductive path, which can be electrically compensated by liquid metal microspheres (LMMSs) upon dynamic deformation. The freestanding ECI conductor demonstrates a breaking strain of ∼1305.5% and a conductivity of ∼5322.7 S cm^-1. The ECI can be universally printed on diversified textiles free of pretreatment, with high permeability (319.2 μm) and low diffusivity (6.2 μm), demonstrating a stable printing line width of ∼216 μm on knitted cotton textiles, while maintaining electrical stability after 200 stretching cycles with 50% strain. Printed electronic textiles with stretchability, high abrasion resistance, and machine washability are demonstrated for wearable applications such as fabric electrodes, capacitive sensors, and electrocardiograph monitoring.