Triple-network-based conductive polymer hydrogel for soft and elastic bioelectronic interfaces

Conductive polymer hydrogels have greatly improved the compatibility of electronic devices with biological tissues for human-machine interfacing. Hydrogels that possess low Young's modulus, low interfacial impedance, and high tensile properties facilitate high-quality signal transmission across dynamic biointerfaces. Direct incorporation of elastomers with conductive polymers may result in undesirable mechanical and/or electrical performance. Here, a covalent cross-linking network and an entanglement-driven network with conductive poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) have been combined. The triple-network conductive hydrogel shows high stretchability (with fracture strain up to 900%), low impedance (down to 91.2 & omega; cm(2)), and reversible adhesion. Importantly, ultra-low modulus (down to 6.3 kPa) and strain-insensitive electrical/electrochemical performance were achieved, which provides a guarantee for low current stimulation. The material design will contribute to the progression of soft and conformal bioelectronic devices, and pave the way to future implantable electronics.