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)-basedhydrogels have emerged as ideal interfacing materials for bioelectronicsbecause of their intriguing electrical, mechanical, and biologicalproperties. However, the development of high-performance PEDOT:PSS-basedhydrogels simultaneously achieving high conductivity, robust mechanicalproperties, and accessibility for advanced manufacturing technologiesremains a critical challenge for further advancing such materialstoward practical applications. Herein, we develop a highly conductive,intrinsically soft, tough yet stretchable PEDOT:PSS-based hydrogelvia a simple PSS-chain engineering strategy of introducing thermallycross-linkable N-(hydroxymethyl)acrylamide segments.The resultant PEDOT:PSS hydrogel exhibits high electrical conductivity(1850 S m(-1)), high stretchability (>50%), lowYoung'smodulus (4 MPa), and superior toughness (400 kJ m(-3)), satisfying multiple property requirements for practical bioelectronicapplications. Based on this material, we further develop a novel PEDOT:PSSink with superior 3D printability for direct ink writing 3D printing,enabling us to facilely fabricate bioelectronic devices like softskin electrodes comparable to commercial products via multi-material3D printing.