Recent advances in stretchable hydrogel-based triboelectric nanogenerators for on-skin electronics

Stretchable hydrogel-based triboelectric nanogenerators (TENGs) have attracted significant attention for their potential in on-skin electronics. Stretchable hydrogels, known for their high flexibility, biocompatibility, and conductive properties, have emerged as crucial components in enhancing the mechanical properties and adaptability of TENGs. These hydrogels, which can withstand continuous deformation, exhibit unique features such as self-healing and high ionic conductivity, making them ideal for on-skin electronics. This review highlights the various types of stretchable hydrogels, including ionic, conductive polymer-based, carbon-based, and metal-based hydrogels, emphasizing their mechanical resilience, electrical properties, and ability to endure continuous deformation. Furthermore, it discusses key strategies for optimizing the structural design of TENGs, ensuring that these systems maintain both efficiency and user comfort during prolonged skin contact. Applications of these technologies in wearable electronics, particularly for health monitoring, HMI, and motion tracking, are explored in depth, highlighting their potential to revolutionize next-generation on-skin devices. Finally, the review addresses ongoing challenges such as material durability and user comfort, and offers perspectives on future research directions.