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

Abstract

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 Ω·cm²), 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.

Keywords

conductive polymer hydrogel / neurostimulation / PEDOT:PSS / triple interpenetrating network / ultrasoft bioelectronics

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