Balancing the mechanical, electronic, and self-healing properties in conductive self-healing hydrogel for wearable sensor applications.

Conductive self-healing hydrogels (CSHs) that match the mechanical properties of biological tissues are highly desired for emerging wearable electronics. However, it is still a fundamental challenge to balance the trade-offs among the mechanical, electronic, and self-healing properties in CSHs. In this study, we presented supramolecular double-network (DN) CSHs by pre-infiltrating conductive polyaniline (PANI) precursor into the self-healable hydrophobic association poly(acrylic acid) (HAPAA) hydrogel matrix. The dynamic interfacial interactions between the HAPAA and PANI networks efficiently enhanced the mechanical performances of the HAPAA/PANI (PAAN) hydrogel and could compensate for the negative effect of the enhanced mechanical strength on self-healing. In addition, the interconnected PANI network endowed the PAAN hydrogel with high conductivity and excellent sensory performances. As such, the mechanical and electronic properties of the PAAN hydrogel were simultaneously enhanced significantly without compromising the self-healing performance of the HAPAA matrix, achieving balanced mechanical, electronic, and self-healing properties in the PAAN hydrogel. Lastly, proof-of-concept applications like human physiological monitoring electronics, flexible touch screens, and artificial electronic skin are successfully demonstrated using the PAAN hydrogel with the capability of restoring their electronic performances after the healing process. It is anticipated that such hydrogel network design can be extended into next-generation hydrogel electronics for human-machine-interfaces and soft robotics.