Tribological Reliability of Polymer Composites for Skin-Interfaced Bioelectronics: Wear-to-Failure Pathways and Testing Framework.

Skin-interfaced bioelectronics rely on soft polymer composites to provide electrical functionality while maintaining the compliance and deformability needed for prolonged contact with the human body. Mechanical durability is commonly demonstrated through stretchability, cyclic deformation and retention of electrical performance under strain, but these measures do not capture contact-induced damage during actual wear. Skin movement, clothing contact and repeated use introduce friction, sliding and abrasion that can produce surface wear, cracking, delamination, conductive-network disruption and instability at the skin-device interface. This review considers tribological reliability as a distinct dimension of wearable durability, linking polymer-composite architecture and interfacial design to the development of wear and its progression into electrical degradation and loss of device function. Evidence across electrophysiological, pressure, strain and biochemical devices shows that material survival, electrical continuity and functional performance do not necessarily deteriorate together, making cycle count or retained conductivity alone insufficient indicators of durability. We propose an application-specific framework that evaluates representative wear conditions together with controlled contact and environmental parameters, morphological damage, electrical stability and preservation of sensing function. Future claims of tribological reliability should therefore be based on whether the required device function is retained under a representative and sufficiently defined wear exposure.