Design of Highly Conductive, Intrinsically Stretchable, and 3D Printable PEDOT:PSS Hydrogels via PSS-Chain Engineering for Bioelectronics

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)-based hydrogels have emerged as ideal interfacing materials for bioelectronics because of their intriguing electrical, mechanical, and biological properties. However, the development of high-performance PEDOT:PSS-based hydrogels simultaneously achieving high conductivity, robust mechanical properties, and accessibility for advanced manufacturing technologies remains a critical challenge for further advancing such materials toward practical applications. Herein, we develop a highly conductive, intrinsically soft, tough yet stretchable PEDOT:PSS-based hydrogel via a simple PSS-chain engineering strategy of introducing thermally cross-linkable N-(hydroxymethyl)acrylamide segments. The resultant PEDOT:PSS hydrogel exhibits high electrical conductivity (1850 S m–1), high stretchability (>50%), low Young's modulus (4 MPa), and superior toughness (400 kJ m–3), satisfying multiple property requirements for practical bioelectronic applications. Based on this material, we further develop a novel PEDOT:PSS ink with superior 3D printability for direct ink writing 3D printing, enabling us to facilely fabricate bioelectronic devices like soft skin electrodes comparable to commercial products via multi-material 3D printing.