Ionic Tactile Sensors for Emerging Human-Interactive Technologies: A Review of Recent Progress

Ionic tactile sensors (ITS) represent a new class of deformable sensory platforms that mimic not only the tactile functions and topological structures but also the mechanotransduction mechanism across the biological ion channels in human skin, which can demonstrate a more advanced biological interface for targeting emerging human-interactive technologies compared to conventional e-skin devices. Recently, flexible and even stretchable ITS have been developed using novel structural designs and strategies in materials and devices. These skin-like tactile sensors can effectively sense pressure, strain, shear, torsion, and other external stimuli with high sensitivity, high reliability, and rapid response beyond those of human perception. In this review, the recent developments of the ITS based on the novel concepts, structural designs, and strategies in materials innovation are entirely highlighted. In particular, biomimetic approaches have led to the development of the ITS that extend beyond the tactile sensory capabilities of human skin such as sensitivity, pressure detection range, and multimodality. Furthermore, the recent progress in self-powered and self-healable ITS, which should be strongly required to allow human-interactive artificial sensory platforms is reviewed. The applications of ITS in human-interactive technologies including artificial skin, wearable medical devices, and user-interactive interfaces are highlighted. Last, perspectives on the current challenges and the future directions of this field are presented.