Fabrication of stretchable circuits with horseshoe-shaped double-layer composite conductive structures via direct ink writing and electrochemical 3D printing technologies

Flexible, stretchable electronics, which possess the remarkable capability to adapt to various deformations, including bending, twisting, and stretching, exhibit extensive potential applications in areas such as flexible sensing and wearable devices. Among these, the stretchable circuit, serving as the core structure that connects various components, plays a pivotal role in determining the performance of the entire flexible and stretchable electronic system. However, there exists an inherent trade-off relationship between the electrical performance and the stretchability of stretchable circuits. In this study, a horseshoe-shaped double-layer composite conductor structure was designed for the fabrication of stretchable circuits using direct writing technology and electrochemical 3D printing technology. This double-layer horseshoe-shaped geometric structure not only improves the electrical performance of the wir but also ensures its mechanical stability during the stretching process. Compared to single-structure stretchable circuits, the stretchable circuits featuring a horseshoe-shaped double-layer composite conductive structure exhibit an enhancement in electrical performance by 2.86 times in the unstretched state and by 4.05 times at a 70% stretch rate. Furthermore, after 1000 cycles of stretching and bending, the resistance change rate remains below 15%. The fabricated stretchable circuits not only maintain superior electrical performance but also demonstrate remarkable stretchability and durability, thereby offering a novel approach for the development of flexible stretchable circuits.