Stretchable graphene–hydrogel interfaces for wearable and implantable bioelectronics

Soft, stretchable and biocompatible conductors are required for on-skin and implantable electronics. Laser-induced graphene (LIG) can offer tuneable physical and chemical properties, and is of particular value in the development of monolithically integrated multifunctional stretchable bioelectronics. However, fabricating LIG-based nanocomposites with thin features and stretchable performance remains challenging. Here we report a thin elastic conductive nanocomposite that is formed by cryogenically transferring LIG to a hydrogel film. The low-temperature atmosphere enhances the interfacial bonding between the defective porous graphene and the crystallized water within the hydrogel. Using the hydrogel as an energy dissipation interface and out-of-plane electrical path, continuously deflected cracks can be induced in the LIG leading to an over fivefold enhancement in intrinsic stretchability. We use the approach to create multifunctional wearable sensors for on-skin monitoring and cardiac patches for in vivo detection.