New flat thermoelectric device converts body heat into electricity

Researchers at Seoul National University College of Engineering have developed a novel flat, flexible thermoelectric device that generates electricity directly from body heat without adding bulk or compromising comfort. Led by Prof. Jeonghun Kwak, the team addressed a key challenge in wearable thermoelectric generators: maintaining a temperature difference in thin, flat devices. Traditional flat wearables allow heat to pass straight through to the air, eliminating the temperature gradient needed for power generation. Previous solutions involved bending or creating 3D structures, which increased thickness and reduced comfort. The breakthrough came from redesigning heat flow rather than device shape. The researchers created a “dual thermal conductivity substrate” by embedding copper nanoparticles into specific regions of a stretchable silicone base, forming zones with different thermal conductivities within a single flat layer. This design directs heat to flow laterally along high-conductivity paths, creating temperature differences across the surface and enabling power generation in a thin, planar form. The device, produced via an ink-based printing method,