Toward Self-Sustained Wearables: Energy Harvesting, Storage, and Smart Power Management

The development of wearable electronic devices is crucial for emerging applications such as continuous health monitoring, human–machine interaction, and mobile sensing. However, their advancement remains fundamentally constrained by energy supply challenges. Limited form factor, strict requirements on comfort, and long-term skin contact impose far more severe trade-offs among power density, safety, and system reliability than those encountered in conventional portable electronics. Moreover, wearable platforms are typically exposed to highly variable operating conditions, where both available energy and load demand fluctuate significantly over time. Based on a narrative review of recent advances in wearable energy harvesting technologies, this paper surveys a broad spectrum of energy sources, including photovoltaic devices, triboelectric and piezoelectric nanogenerators, biofuel cells, wireless power transfer and flexible lithium-ion battery schemes. Building upon this analysis, the paper summarizes common design principles of energy conditioning circuits, including rectification, impedance matching, power conversion, and energy routing strategies, which achieve reliable operation with low power consumption. Beyond circuit-level design, AI-based battery management strategies are discussed as an emerging layer to cope with energy intermittency, workload variability, and lifetime degradation under strict computational constraints. By integrating energy harvesting, interface circuit design, and intelligent management into a unified system-level perspective, this review provides design insights and guidance for the development of robust, adaptive, and sustainable wearable energy management systems.