Humanoid Ionotronic Skin for Smart Object Recognition and Sorting

Nowadays, there is an urgent need for humanoid robots containing human finger-like electronic skins with mechanical endurance and tactile perception. This study reports the development of an ionotronic skin-based humanoid robot hand that can recognize objects precisely through finger tapping or touching. The ionotronic skin is composed of a cytoskeleton-like filament network structure and possesses mechanical properties highly akin to human skins, including softness (Young's modulus of 51 +/- 15 MPa), toughness (1.6 +/- 0.7 MJ m-3), and antifatigue-fracture ability. In addition, the i-skin functions as a triboelectric nanogenerator with the ability to perceive the triboelectric signals of an object when in contact with it. By combining triboelectric sensing information, machine learning, and Internet of Things techniques, the humanoid robot hand can accurately recognize different materials among a diverse set of spherical objects and further deliver them to the designated location. The high sorting success rate of 97.2% in 600 tests of recognizing five types of spherical objects, together with the outstanding mechanical and environmental tolerance, allow such humanoid robot hands to be used for intelligent sorting, automatic operation, and assembly in unmanned factories, as well as for the classification of garbage and hazardous materials.