High-Sensitivity and Linear-Response EDL-Based Iontronic Skins: Structural Design and Emerging Applications

Abstract

Biological skin provides humans with sophisticated tactile perception, enabling precise object recognition and texture discrimination. Inspired by this, iontronic skins have emerged as a high-performance sensing platform that converts mechanical stimuli into electrical signals via the dynamic modulation of electric double-layer (EDL) capacitance. To fulfill the rigorous performance requirements of intelligent robotics and wearable healthcare, the simultaneous optimization of sensitivity and response linearity has become a primary research focus. In this review, focuses specifically on EDL-based iontronic skins, with particular emphasis on the latest advancements in structural engineering and emerging applications. Central to this work is the establishment of a physics-grounded taxonomy that categorizes iontronic architectures into four topological classes based on the dimensionality of their contact evolution: point-contact (0D), line-contact (1D), surface-contact (2D), and volumetric-contact (3D) structures. We elucidate how these topological dimensions govern the fundamental scaling laws of contact area expansion and unit-area capacitance modulation, providing a systematic framework for principle-driven sensor design. Furthermore, transformative applications in personalized healthcare, robotic interfaces, and human–machine interaction are systematically discussed. Finally, we address prevailing challenges, including the transition toward large-scale high-density integrated systems, long-term environmental stability, and scalable manufacturing, while outlining future research directions to bridge the gap between laboratory prototypes and commercialized intelligent systems.