Three-dimensional printing of multilayer stretchable electronics with inclined interconnect accesses

Multilayer stretchable electronics offer revolutionary potential for next-generation smart wearables, soft robotics and human-machine interfaces, but they face considerable challenges in achieving reliable three-dimensional (3D) interconnections with satisfied stretchability, stability and manufacturing efficiency. Herein, we report additive manufactured (3D printed) multilayer stretchable electronics with unpunched inclined interconnect accesses. Contrary to the widely adopted subtractive manufactured electronics with punched vertical interconnections, the printed interlayer access with inclined geometry effectively mitigates stress concentration and minimizes Poisson effect-induced deformation, thus ensuring stable mechanical and electrical properties. In addition, the 3D printing strategy also significantly promotes the design freedom with rapid manufacturing process. As a result, such 3D printed multilayer electronics illustrate high stretchability (646% strain limit) and excellent stability (over 11000 cycles at 100% strain), surpassing previously reported multilayer stretchable devices. A wireless-powered display system maintains stable performance under large-scale stretching, and a four-layer conformal physiological monitoring system is also demonstrated.