Non-contact triboelectric nanogenerators for energy-information systems: Charge-lifecycle engineering, system integration, and sustainability perspectives

The increasing demand for distributed and low-maintenance sensing networks has accelerated the development of integrated energy-harvesting and sensing technologies capable of converting ambient mechanical disturbances into electrical energy and sensing signals. Triboelectric nanogenerators (TENGs) have emerged as promising platforms for converting low-frequency mechanical stimuli into electrical signals; however, conventional contact-mode structures suffer from friction-induced degradation, surface contamination, and limited durability during long-term operation. Non-contact TENGs (NC-TENGs) address these limitations by replacing continuous solid-solid interaction with air-gap-mediated electric-field coupling, enabling reduced mechanical wear and integrated energy conversion and sensing. Nevertheless, the absence of direct contact introduces inherent challenges associated with weakened electrostatic coupling, charge retention, and output stability. This review establishes a charge-lifecycle-oriented framework to understand the performance evolution and optimization of NC-TENGs, with non-contact electrostatic coupling discussed as the physical basis for energy conversion and signal generation. Representative device configurations are compared, followed by a discussion of charge-lifecycle engineering strategies, including charge-generation, charge-trapping enhancement, leakage suppression, and charge compensation. Beyond device-level optimization, recent advances in NC-TENG-enabled energy-information applications are summarized, including distributed IoT systems, wearable interfaces, robotic perception and human-machine interaction, environmental energy harvesting networks, and industrial infrastructure monitoring. Finally, the remaining challenges associated with reliable operation, energy management, and system-level deployment are discussed to provide perspectives for the future development of durable and scalable NC-TENG technologies.