Designing PEDOT:PSS hydrogels for bioelectronic interfaces

Conductive hydrogels have emerged as promising materials for wearable and implantable bioelectronic interfaces because they combine tissue-like mechanical properties with efficient signal transduction. Among them, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has attracted significant attention owing to its dual ion–electron conductivity, biocompatibility, and solution processability. However, practical bioelectronic applications require hydrogel electrodes to simultaneously achieve high conductivity, mechanical robustness, strong adhesion, self-healing capability, environmental and physiological stability, biocompatibility, and long-term conformal contact with biological tissues. Despite substantial progress in PEDOT:PSS hydrogels, a comprehensive understanding of how material structure and engineering strategies govern these functional requirements still remains elusive. This review systematically discusses the fundamental requirements for PEDOT:PSS hydrogels to function as high-performance hydrogel electrodes, as well as the corresponding material design strategies with trade-offs. Current challenges and future opportunities, including robust soft-to-rigid interconnections, asymmetric adhesion, transparent biointerfaces, machine learning-assisted systems, and multimodal decoupling strategies, are highlighted. Overall, this review provides a comprehensive design roadmap for developing next-generation PEDOT:PSS hydrogel bioelectronic interfaces.