Self-Assembly Enabled Printable Asymmetric Stretchable Conductor for Human Interface

Soft and stretchable conductors with high electrical conductivity and mechanical properties comparable to biological tissues are essential for the development of wearable and implantable bioelectronic devices. Liquid metal-based conductors are particularly promising due to their intrinsic metallic conductivity and low mechanical stiffness. However, the formation of a continuous conductive network within polymer matrices is often hindered by surface oxidation of the liquid metal particles, limiting the electrical performance of these composites. In this work, we report a printable composite material based on liquid metal and conducting polymer that undergoes a self-assembly process, achieving high conductivity (2089 S cm^-1) in the bottom surface while maintaining an insulated top surface, high stretchability (>800%), and a modulus akin to human skin tissue. The utility of this material is demonstrated through the fabrication of skin-interfaced strain sensors and electromyography sensors using 3D printing techniques, highlighting its potential for biomedical applications.