Bioinspired Janus Heterogeneous Fibrous Membranes for Wearable Moisture‐Electric Energy Harvesting via a Plant‐Transpiration Mechanism

Harvesting energy from the ubiquitous environmental water vapor cycle is a promising pathway for sustainable power generation. Human skin releases ≈40–340 W of thermal energy per hour through perspiration, and even converting 1% could power most low‐energy wearable devices. However, achieving stable vapor capture, directional transport, and efficient charge separation in the skin microenvironment remains a key challenge for hygrothermal energy conversion. Inspired by plant transpiration, a bioinspired moisture‐guiding heterogeneous interface is constructed to fabricate a Janus Alk‐MXene PVA@Alk‐PVA‐PVDF fibrous membrane with hydrophilic adsorption, ion conduction, and evaporation‐driven traction, enabling directional vapor transport and efficient charge separation. With a thickness of 0.084 mm, the membrane combines flexibility, breathability, and excellent integration compatibility for wearable applications. A 1 cm 2 Janus MEG delivers a rapid response of 1.07 s, 1.18 V output, ≈935.2 µA cm −2 short‐circuit current density, and ≈1103.5 µW cm −2 power density, retaining ≈0.87 V after one month and demonstrating excellent moisture sensitivity with stable voltage output. Furthermore, a modular three‐unit series–parallel configuration achieves ≈2.32 V and ≈46.4 mA under high humidity, providing a sustainable strategy for self‐powered wearable electronics in medical monitoring and next‐generation human–machine interaction.