Pure PEDOT:PSS hydrogels

TLDR

Hydrogels of conducting polymers, especially PEDOT:PSS, offer a promising electrical interface with biological tissues because of their favorable electrical and mechanical properties, but blending with non‑conductive polymers often compromises these attributes. This study demonstrates that creating interconnected networks of PEDOT:PSS nanofibrils through a simple fabrication approach yields high‑performance pure PEDOT:PSS hydrogels. The fabrication method mixes volatile dimethyl sulfoxide into aqueous PEDOT:PSS, then applies controlled dry‑annealing followed by rehydration to form the nanofibril network. The resulting hydrogels exhibit high conductivity (~20 S cm⁻¹ in PBS, ~40 S cm⁻¹ in deionized water), stretchability over 35 % strain, a low Young’s modulus (~2 MPa), and superior mechanical, electrical, and electrochemical stability, with tunable isotropic or anisotropic swelling in wet physiological environments.

Abstract

Abstract Hydrogels of conducting polymers, particularly poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), provide a promising electrical interface with biological tissues for sensing and stimulation, owing to their favorable electrical and mechanical properties. While existing methods mostly blend PEDOT:PSS with other compositions such as non-conductive polymers, the blending can compromise resultant hydrogels’ mechanical and/or electrical properties. Here, we show that designing interconnected networks of PEDOT:PSS nanofibrils via a simple method can yield high-performance pure PEDOT:PSS hydrogels. The method involves mixing volatile additive dimethyl sulfoxide (DMSO) into aqueous PEDOT:PSS solutions followed by controlled dry-annealing and rehydration. The resultant hydrogels exhibit a set of properties highly desirable for bioelectronic applications, including high electrical conductivity (~20 S cm −1 in PBS, ~40 S cm −1 in deionized water), high stretchability (> 35% strain), low Young’s modulus (~2 MPa), superior mechanical, electrical and electrochemical stability, and tunable isotropic/anisotropic swelling in wet physiological environments.