ICT2014 Abstracts

The conversion of body heat into electrical energy by a flexible thermoelectric (TE) power generator is useful for self-powered wearable mobile electronic systems. The flexible TE generator requires high mechanical and electrical stabilities under repeated tensile and compressive strains. Organic TE materials have been focused in the past years due to its high flexibility but, organic-based TE generators exhibit low output power density that is far below the requirements for wearable electronic devices, caused by several limitations of the polymer: a low power factor, high contact resistance with a metal electrode. On the other hand, a relatively thick and bulky external substrates being used in commercial TE generators cause serious thermal energy loss and eventually decreases output power density. In this work, we report a flexible TE generator fabricated on glass-fabric, realizing a truly wearable TE generator that is not made with organic materials but rather inorganic TE materials that can provide high output power. Screen printing technique and glass fabric were used for the innovative self-sustaining structure of a TE device without top and bottom substrates, and enable a thinner (~500 μm), lighter (~0.13 g/cm²), and more flexible device than the TE devices reported to date. A prototype, integrating an array of 8 thermocouples (n-type Bi₂Te₃ film and p-type Sb₂Te₃ film), was fabricated and evaluated as a wearable TE generator. The developed device not only achieved large output power density (1400% increase in W/g, compared to the conventional ceramic substrate TE generator) but also shows an allowable bending radius of as low as 20 mm and no change in performance upon repeated bending for up to 120 cycles.