A water-retaining, self-healing hydrogel as ionic skin with a highly pressure sensitive properties.

• Ionic skin was designed as hydrogel with sandwich's structure. • The addition of SDBS results in the formation of a unique graded porous structure. • Ionic skin can monitor subtle pressure changes in the body. • Ionic skin can heal itself within 2 s after breaking. In recent years, artificial skin materials have attracted increasing attention of researchers in the field of wearable devices, artificial robot, artificial intelligence and other fields. However, the skin possesses multiple functions as the largest human organ, so there is still tremendous challenge in mimicking human skin. In this work, we successfully fabricated a skin sensor by constructed a sandwich structure to introduce a PDMS (polydimethylsiloxane) as water-retaining layer into sodium dodecylbenzene sulfonate (SDBS) and Bimetallic ion (Fe³⁺, Al³⁺) prepared flexible hydrogel to maintain moisture. The results manifested that he average dehydration rate of the hydrogel was reduced by more than 97%, due to the coating of PDMS, compared to the uncoated hydrogel. More importantly, the addition of SDBS results in a graded porous structure of the hydrogel, which facilitates the transport of ions and thus achieves pressure-sensitive behavior such as pulse rhythm, sound vibration and joint bending. Additionally, the hydrogel fabricated by the bimetallic ion as a crosslinking agent has high mechanical strength and self-healing properties that can self-heal within 2 s without any stimulation, wherein the self-healing efficiency is as high as 95%. As-prepared the artificial skin can not only be applied to various fields such as artificial intelligence, sensors, and personal medical care, but also promotes the further development and exploits great potential applications of smart skin. [ABSTRACT FROM AUTHOR]