Extrusion 3D printing of conjugated polymers

Conjugated polymers combine electronic charge transport properties with the ability to transport ions, enabling transduction between ionic and electronic currents. Many applications of conjugated polymers, such as biointerfaces, actuators, and energy storage, benefit from 3D structures. Among different methods for 3D fabrication, extrusion-based 3D printing is a versatile approach that is compatible with multimaterial fabrication processes. This review summarizes progress in the emerging field of 3D printed conjugated polymers using three extrusion printing processes: direct ink write, meniscus-guided printing, and electrohydrodynamic printing. Ink designs for direct in write are described in depth, including strategies for modifying the rheology and conductivity of the inks.