Photopatternable PEDOT:PSS Hydrogels for High‐Resolution Photolithography

Conducting polymer hydrogels have been extensively explored toward diverse applications like bioelectronics and soft robotics. However, the fabrication resolution of conducting polymer hydrogels by typical techniques, including ink-jet printing, 3D-printing, etc., has been generally limited to >10 µm, significantly restricting rapid innovations and broad applications of conducting polymer hydrogels. To address this issue, a photosensitive biphasic conducting polymer hydrogel (PB-CH) is rationally designed and synthesized, comprising poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as the conductive phase and a light-sensitive matrix as the mechanical phase. The formation of phase-separated structures within PB-CH preserves the integrity of the conductive channels during the photoinitiated cross-linking. This minimizes the conductivity loss, a common limitation in similar materials. Remarkably, the resultant PB-CH exhibits a combination of excellent electrical conductivity (≈30 S cm^-1), robust mechanical performance (tensile strain up to 50%), and high photopatternability. A detailed investigation of the photolithography process identifies key technological parameters that enable high-resolution patterning of 5 µm. By simultaneously maintaining processability, conductivity, and mechanical flexibility, this PB-CH represents an ideal candidate for advanced flexible electronic applications, offering a new technique to fabricating high-performance conducting polymer hydrogels.