Milliwatt-Scale Body-Heat Harvesting Using Stretchable Thermoelectric Generators for Fully Untethered, Self-Sustainable Wearables

Stretchablethermoelectric generators (s-TEGs) have beenregardedas promising energy harvesters for self-powered wearable electronics.However, previous s-TEGs show low power generation capacity due totheir high module resistances, originating from the poor electromechanicalinterfaces between rigid-soft components and the high electricalresistances of stretchable interconnects. Herein, we report strategiesto boost thermoelectric performance, which allows us to operate wirelesscommunication systems from body heat by generating a power of 2.6mW. Electromechanically graded interlayers that mediate discrete functionalitiesat the interfaces effectively reduce junction resistances, and solution-basedwelding that transforms scattered networks into mesh-like structuresproduces highly conductive and strain-resilient interconnects, respectively.Soft heat conductors are included to improve thermal interfaces, minimizingthermal impedance of elastomeric substrates. Consequently, the powergeneration capacity is significantly enhanced, exhibiting the highestnormalized power density of 1.48 mu W cm(-2) K-2 among reported high-performance s-TEGs. Our s-TEGsprovide realistic solutions for sustainable self-powered electronics.

Automated summary

Stretchable thermoelectric generators (s-TEGs) have been regarded as promising energy harvesters. This study reports strategies to boost thermoelectric performance, enabling wireless communication systems to be powered by body heat with a power generation of 2.6mW. These strategies include the use of electromechanically graded interlayers, solution-based welding, and the inclusion of soft heat conductors. These improvements significantly enhance the power generation capacity of s-TEGs, exhibiting the highest normalized power density among reported high-performance s-TEGs. This research provides realistic solutions for sustainable self-powered electronics.