Ambient Moisture as Energy Source: MEG Technology toward Self-Powered Wearable Sensors

Wearable sensing technologies face persistent challenges in power supply miniaturization, sustainability, and environmental adaptability. Moisture-enabled electricity generation (MEG), harnessing ambient humidity for electricity, offers a breakthrough for self-powered systems. This review summarizes recent advances in MEG materials, structural design, and wearable sensing applications. The energy conversion mechanisms rely on ion gradient diffusion and streaming potential, enhanced by active material optimization (e.g., carbon materials, biomaterials, synthetic polymers, and inorganic metal oxides) for humidity sensitivity and ion mobility. Device designs incorporating heterostructures, porous architectures, flexible substrates, and system integration improve output stability and wearability. Hybrid systems combining MEG with triboelectric or thermoelectric effects further boost energy efficiency. These advancements enable self-powered sensing applications in real-time health monitoring, human-machine interaction, and environmental parameter detection. Currently, MEG-based sensing still faces challenges in terms of power density, dynamic interference, and durability. Future research should prioritize material innovation, system integration for miniaturization, and synergistic coupling with AI-driven data analytics to achieve autonomous, intelligent wearables. This work provides insights into the development of next-generation self-sustaining sensing technologies, highlighting MEG's transformative potential in bridging energy autonomy with wearable innovation.