Liquid Metal‐Based Solar Energy Harvesting and Conversion Materials for Thermal Detection and Measurement

ABSTRACT This work introduces a conceptual advancement in solar‐powered thermal detection and measurement through a rationally designed multifunctional liquid metal‐based elastomer material system. Unlike conventional methods that rely on rigid, energy‐intensive, or wire‐dependent devices, this system uniquely combines a photothermal film with high solar absorptance (85.1%) and a highly thermally conductive liquid metal‐based composite, enabling flexible, self‐powered, and real‐time operation in remote or non‐electrified environments. The photothermal film, featuring low thermal conductivity, enables passive visualization of subsurface heterogeneities, such as cracks, impurities, or hydration states‐by converting spatially varying thermal conductivity into distinct surface temperature patterns detectable by an infrared camera. Furthermore, by integrating this film with a thermoelectric generator and a high‐thermal‐conductivity liquid metal composite, we develop a real‐time thermal conductivity measurement device that operates solely under sunlight. This device exhibits a sensitivity of 35 mV across a thermal conductivity range of 0.27–12.91 W·m −1· K −1 , with good mechanical and thermal stability. Together, these demonstrations establish a new platform for soft, solar‐driven thermal sensing systems, addressing critical gaps in portable environmental and biomedical monitoring.