Soft and Stretchable Thermoelectric Generators Enabled by Liquid Metal Elastomer Composites

Abstract

Stretchable thermoelectric generators (TEGs) capable of harvesting electrical energy from body heat under cold weather conditions have the potential to make wearable electronic and robotic systems more lightweight and portable by reducing their dependency on on-board batteries. However, progress depends on the integration of soft conductive materials for robust electrical wiring and thermal management. The use of thermally conductive soft elastomers is especially important for conforming to the body, absorbing body heat, and maintaining a temperature gradient between the two sides of the TEGs in order to generate power. Here, we introduce a soft-matter TEG architecture composed of electrically and thermally conductive liquid metal embedded elastomer (LMEE) composites with integrated arrays of n-type and p-type Bi2Te3 semiconductors. The incorporation of a LMEE as a multifunctional encapsulating material allows for the seamless integration of 100 thermoelectric semiconductor elements into a simplified material layup that has a dimension of 41.0 × 47.3 × 3.0 mm. These stretchable thermoelectric devices generate voltages of 59.96 mV at Δ10 °C, 130 mV at Δ30 °C, and 278.6 mV and a power of 86.6 μW/cm2 at Δ60 °C. Moreover, they do not electrically or mechanically fail when stretched to strains above 50%, making them well-suited for energy harvesting in soft electronics and wearable computing applications.