Decoding UV exposure history from material state evolution with a light memory hydrogel triboelectric sensor

ZnO nanoparticles enable photoresponsive ionic hydrogels with light memory • Light-memory hydrogel TENG records recent UV exposure history • Temporal UV exposure is reconstructed from evolving material states • WMPT-Mamba identifies five UV irradiance levels with 98.6% accuracy • Self-powered wearable patch enables real-time UV monitoring and risk warning Prolonged solar ultraviolet (UV) exposure poses a growing occupational health burden, particularly for outdoor workers, yet personal UV risk is inherently cumulative and difficult to capture using sensors that primarily report instantaneous light conditions. Photoresponsive triboelectric nanogenerators (Photo-TENGs) offer a self-powered route for wearable light sensing, but their material responses have largely been exploited to enhance electrical output during illumination, leaving post-illumination state evolution underutilized as a source of exposure-history information. Here, a light-memory hydrogel triboelectric sensor (LM-gel-TENG) is developed to retain recent UV exposure through time-dependent material-state evolution. A ZnO-integrated ionic hydrogel is designed to synergistically combine mechanical adaptability, ion transport, and photoinduced charge regulation, enabling electrically readable UV-responsive triboelectric signals and persistent electrical-state enhancement after illumination. An output voltage of 228 V and a maximum photoinduced voltage enhancement of 44.86% are achieved by the LM-gel-TENG. The evolving signals are reconstructed into dark-light-memory pulse triplets, and a Wavelet-Markov Pulse-Triplet Mamba framework is developed to distinguish five UV irradiance levels with 98.6% accuracy. A mobile platform further enables real-time signal acquisition and visualization, post-event classification of five predefined UV irradiance levels, digitally calculated cumulative-dose display, and exposure-risk indication, supporting personalized wearable UV monitoring. By decoding post-illumination material-state evolution as temporal exposure information, this work advances Photo-TENGs toward exposure-history-aware self-powered sensing and offers a pathway for more individualized UV exposure awareness and proactive protection in populations facing sustained outdoor work. A light-memory hydrogel triboelectric sensor converts UV-induced material-state evolution into decodable electrical signals, achieving 40.96% voltage enhancement and light-signal retention. Integrated with WMPT-Mamba recognition and a mobile app/LED warning platform, the intelligent patch enables real-time personalized UV exposure monitoring and risk warning. Download: Download high-res image (224KB) Download: Download full-size image