All 3D Printed Soft Integrated Conductors

Soft integrated circuits, which possess mechanical properties similar to skin, hold significant potential in human-machine interface sensing and biomedical devices. The complex manufacturing techniques required for their multilayer circuit structures impose limitations on the application and innovation of flexible integrated circuits. This paper introduces a composite ink developed from the conductive polymer PEDOT:PSS (3,4-ethylenedioxythiophene/styrenesulfonate) and the hydrated matrix polymer PAAm (polyacrylamide). This ink demonstrates remarkable printability and is well-suited for high-resolution direct ink writing (DIW) 3D printing. A simple cross-linking process enables the transformation of the ink into a high-performance conductive hydrogel. Following post-treatment, the 3D-printed hydrogel exhibits a conductivity of 62 S/m in its gel state and 311 S/m in its dry gel state, along with a strain capacity of 210%. Furthermore, it maintains high stability in water, allowing for sustained performance over extended periods. Multifunctional integration of miniature 3D circuits is facilitated through printing, which enables the wireless transmission of electrical signals. Due to its outstanding biocompatibility, this material presents significant prospects for applications in implantable electronic engineering.