Polyionic Liquid/Poly(3,4-ethylenedioxythiophene)-Based Mixed Ionic and Electronic Conductive Hydrogel for Digital Light Processing 3D Printing

Mixed ionic and electronic conductive hydrogels have demonstrated significant application potential in biosensing, healthcare, and other fields. However, the lack of stable conductive pathways during processing and incompatibility with advanced manufacturing techniques hinders their practical advancements. Herein, we demonstrate a mixed conductive hydrogel that can be 3D printed via Digital Light Processing (DLP), where the electronic conductive pathway is composed of PEDOT:PSS and the ionic conductive pathway is formed by the photocurable polyionic liquid (PIL) (i.e., poly(1-2-acryloyloxy-ethyl)-3-methyl-imidazolium bromide, PAEMIBr). This hydrogel exhibits excellent mixed conductivity (430 mS/m for electronic conductivity and 26 mS/m for ionic conductivity), as measured by electrochemical impedance spectroscopy (EIS), high shape-defined printing resolution (100 μm), and flexibility, with the conduction pathways of printed structures remaining uninterrupted after post-treatment (i.e., annealing and reswelling), providing insights for material design in flexible electronics and sensors.