Integrated material–process–performance 3D printing of multilayer soft electronics using stretchable conductors

Three-dimensional (3D) printing technology enables the rapid manufacturing of complex prototypes and customized soft electronics. However, the integrated manufacturing of multilayer, multimaterial, and multifunctional soft electronics via 3D printing remains challenging due to insufficient synergy between material development and process innovation, as well as inadequate compatibility between stretchable conductors and substrates. Herein, we propose a material-process-performance integrated manufacturing strategy for multilayer soft electronics. Firstly, we develop a novel stretchable conductor with strong interfacial bonding to stretchable substrates. By regulating its rheological properties, the material becomes compatible with 3D printing processes. The stretchable conductor employs 3D clustered silver nanoparticles with large surface area and low aspect ratio as fillers, effectively addressing the inherent trade-off in the performance of stretchable conductors. This design simultaneously achieves high stretchability, conductivity, and low hysteresis. Secondly, we propose a manufacturing strategy combining multi-material 3D printing with sacrificial layer assistance. By leveraging the good thixotropy of the stretchable conductor, the direct formation of 3D stretchable interconnects between layers is enabled, ultimately achieving customized and integrated manufacturing of multilayer soft electronics. Through applications such as multilayer infrared encryption devices and wearable wristbands, we demonstrate the feasibility of the proposed stretchable conductor and integrated manufacturing strategy.