Skin-Inspired Relative Elastic Contact Coefficient Toward Electroluminescent Tactus.

Skin perceives touch by transmitting mechanical stimuli through a hierarchically organized, gradient-modulus architecture that concentrates stress and localizes deformation to activate mechanoreceptors. Inspired by the hierarchical architecture of skin, modulus engineering has been introduced into artificial tactile systems. However, how stress transmission governs internal electric-field distributions-and how the coupling can be exploited for intelligent tactile perception-remain largely unexplored. Here we report a skin-inspired, gradient-modulus electroluminescent pressure display that directly converts mechanical inputs into spatially resolved optical signals. Guided by Hertzian contact theory, we uncover gradient-modulus-induced stress focusing and deformation localization, which in turn redistributes the internal electric field and sensitizes the emissive layer to pressure. This mechano-electro-optical coupling enables intuitive visualization of tactile stimuli. Furthermore, the resulting spatiotemporal luminescence patterns provide rich information for intelligent tactile recognition. Our results establish a general strategy to bridge mechanical perception and optical output, offering a conceptual route toward visualized electronic skin and next-generation human-machine interfaces.