Biomimetic Electronic Skin through Hierarchical Polymer Structural Design

Human skin comprises multiple hierarchical layers that perform various functions such as protection, sensing, and structural support. Developing electronic skin (E-skin) with similar properties has broad implications in health monitoring, prosthetics, and soft robotics. While previous efforts have predominantly concentrated on sensory capabilities, this study introduces a hierarchical polymer system that not only structurally resembles the epidermis-dermis bilayer structure of skin but also encompasses sensing functions. The system comprises a polymeric hydrogel, representing the dermis, and a superimposed nanoporous polymer film, forming the epidermis. Within the film, interconnected nanoparticles mimic the arrangement of interlocked corneocytes within the epidermis. The fabrication process employs a robust in situ interfacial precipitation polymerization of specific water-soluble monomers that become insoluble during polymerization. This process yields a hybrid layer establishing a durable interface between the film and hydrogel. Beyond the structural mimicry, this hierarchical structure offers functionalities resembling human skin, which includes (1) water loss protection of hydrogel by tailoring the hydrophobicity of the upper polymer film; (2) tactile sensing capability via self-powered triboelectric nanogenerators; (3) built-in gold nanowire-based resistive sensor toward temperature and pressure sensing. This hierarchical polymeric approach represents a potent strategy to replicate both the structure and functions of human skin in synthetic designs. A hierarchical polymer system with a bilayer structure is successfully fabricated through a simple and robust in situ interfacial precipitation polymerization process. This bilayer structure closely mimics the structure of the epidermis and dermis in human skin. Integrating a gold nanowire-based temperature and pressure sensor yield a biomimetic electronic skin with built-in sensory functions resembling human skin.image

Automated summary

This study introduces a hierarchical polymer system that mimics the structure and functions of human skin, including protection, tactile sensing, and temperature/pressure sensing capabilities.