Bio-Based Self-Healing Polyurethane Coatings for Electronic Skin: From Dynamic Network Design to Embodied Intelligent Applications

Abstract

As a crucial intersection of flexible electronics and embodied intelligent robotics, electronic skin is evolving from single flexible sensors toward a skin-like intelligent system integrating flexible support, signal sensing, environmental protection, signal transmission, and intelligent feedback. With expanding application scenarios, materials must simultaneously meet requirements for softness, stretchability, high strength, self-healing, wear resistance, and long-term stability. Bio-based self-healing polyurethane, leveraging tunable soft–hard segment structures, a wide range of mechanical properties, facile dynamic bond formation, and renewable raw materials, offers a novel material design pathway for highly reliable electronic skin. This review examines the structural and performance modulation of bio-based components—such as castor oil, nanocellulose, lignin, chitosan, tannic acid, and vanillin—in polyurethane coatings, analyzes the mechanisms of non-covalent interactions, dynamic covalent bonds, and multi-dynamic networks in segment motion, energy dissipation, damage repair, and interface reconstruction, and further discusses their adaptation strategies in encapsulation layers, sensing layers, circuit layers, and base layers. Particular attention is paid to polyurethane coatings as protective and functional interface layers, where coating structure, adhesion, mechanical durability, and damage recovery determine the long-term reliability of electronic skin devices. Finally, this review summarizes current challenges in multi-performance synergy, conductive network stability, bio-based component consistency, long-term service, and large-scale fabrication, while envisioning future directions such as intelligent encapsulation, multi-layer synergy, and data-driven material design.