Multiscale Interfacial Designed Ionogel/Leather Ionic Skin for Multimodal Sensing Capability

Ionic skins with perception capabilities similar to natural skin are compelling candidates for monitoring physiological signals. The green leather containing rich interspaces among dense collagen fibers is a promising skeleton to load soft ionic gels for constructing ionic skins. However, such ionic skin is still plagued by a weak interior combination of the two components and inhomogeneous conductivity. Herein, a multiscale interfacial designed ionogel/leather ionic skin with uniform ionic conductivity is prepared by incorporating ionic liquid (IL) into the polyvinyl alcohol (PVA)-polyacrylamide (PAM)/Leather composite to construct strong interior bonding and continuous ionically conductive paths. The ionic liquid induces volume shrinkage accompanied by dense entanglements of PVA-PAM polymer chains and collagen fibers, together with polymer-rich domains associated by hydrogen bonds among various functional groups, contributing to a strong and tight combination of soft PVA-PAM/IL ionogel matrix and tough leather skeleton. The bonding force between the two components is increased by 2.5 times. Such integration confers the resultant ionic skin with applications in wearable strain, temperature, and respiration sensing. This study enhances the overall performance of the ionogel/leather ionic skin and expands its applications for continuous monitoring of multiple physiological signals.