New technology targets world's highest thermoelectric generator performance

Stretchable, highly efficient thermoelectric generator gasket

A thermoelectric generator is a device that converts heat energy into electrical power using the Seebeck effect. 

The Seebeck effect is a voltage differential caused by a temperature variation between two dissimilar electrical conductors or semiconductors. In a thermoelectric generator, this voltage difference is used to generate an electric current, thus producing electrical power.

The team's major goal was to develop a thermoelectric generator with better efficiency and stretchability, ideal for use on curved surfaces such as skin or hot water pipes. Conventional thermoelectric generators rely heavily on stiff ceramic printed circuit boards, which makes adaption to curved surfaces difficult.

Interestingly, the scientists increased the stretchability of thermoelectric generators by a remarkable 35 percent by adding a deformable gasket with a metastructure.

The use of a metastructure improves the thermoelectric generator's structural stability, allowing it to easily adapt to diverse geometries and demonstrate exceptional stretchability. 

Furthermore, the efficient insulation provided by the gasket's partial air gap reduces heat loss, increasing the thermoelectric generator's efficiency. When compared to currently existing flexible thermoelectric generators, this results in a staggering 30 percent increase in temperature differential.

Dr Hyekyoung Choi of KERI stated: "Researchers in the team not only have the know-how to develop high-performance thermoelectric materials but also have modularization technology dedicated to energy harvesting and technology related to stable self-powered devices."

Choi added: "With such convergence research, we were able to create synergy and consider everything from core technology development, and testing to real-life applications."

 The findings were reported on August 24 in the journal – Advanced Energy Materials.

Study abstract:

Wearable thermoelectric generators (WTEGs) have relied on soft encapsulation materials typically used for the structural support of thermoelectric legs. Heat loss through the filler and low heat transfer via the mismatched contact with the skin causes a small temperature gradient between the human body (hot side) and the natural environment (cold side). Instead of using soft encapsulation materials, a partially air-filled deformable gasket is purposed for leg support, achieving the thermal isolation of thermoelectric legs by preventing parasitic heat transfer. The WTEG comprising the deformable gasket exhibits a 30% larger temperature gradient than that with conventional encapsulant structures filled with soft materials. Additionally, the deformable gasket shows an auxetic metastructure owing to its negative Poisson's ratio, reversibly responding to changes in their environment, which is suitable for skin-like stretchable wearable devices. The band type of WTEG with the optimized leg geometry and fill factor shows a power output of 2 uW cm−2 for eight pairs of thermocouples, a record-high value among the stretchable TEGs obtained indoors at room temperature (23 °C) without wind. This approach paves the way for the efficient conversion of thermal energy into electrical energy and broadens potential applications for self-powered wearable electronics.