The Elephant Trunk Skin Inspires a Highly Sensitive and Deformable, Yet Robust, Armor Skin

Soft artificial skins attract significant attention due to the inherent high deformability and tactile sensing functions, making them highly beneficial for skin-attachable electronics and robotics. However, they have limited mechanical robustness, which is a requirement for real-world applications. Therefore, an evolution to soft "armor skins" is necessary, where deformation, tactile sensitivity, and ruggedness co-exist. We look at the elephant trunk skin as a remarkable model that due to its unique hierarchical structure deforms freely accommodating the trunk versatile motions while maintaining mechanical robustness, providing protection while also allowing for highly sensitive touch. Inspired by this we present the elephant trunk-inspired armor skin with tactile sensing (ETATS), which exhibits high deformability, resistance to puncture and tear, tactile and strain sensing capability. The ETATS consists of a folded soft substrate reinforced with aligned fibers, capable of 60% stretchability of 40% compressibility in lateral direction, combined with a rigid hexagonal island array for strong puncture resistance (97.5 N). Morphology-based decoupling of strain and pressure enables large-area pressure and lateral strain sensing in real-time by embedded optical waveguides. Our strategy maximizes the stretchability, protective capability, and sensing performance of electronic skin, making it highly beneficial for applications in both humans and robots.