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.