Analysis of Skin-Worn Thermoelectric Generators for Body Heat Energy Harvesting to Power Wearable Devices

The rapid growth of wearable electronic devices motivates investigation of powering such devices using energy harvesting, with the long-term goal of continuous operation without the need to recharge or replace batteries. In this work, we present a study conducted using a wearable device to measure the voltage, power, and energy that can be harvested continuously from human body heat using a thermoelectric generator (TEG) worn on the skin surface. Using a TEG worn on the arm, we demonstrate an average of 22.9 μW continuous maximum power delivery across three subjects, corresponding to 1.43 μW/cm
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power density. Additionally, the large thermal gradient across the TEG when first placed on the skin provides sufficient voltage output across a matched load to enable cold start of state-of-the-art DC-DC boost converters. Overall, the results demonstrate sufficient power density and voltage output provided by centimeter-scale TEGs for operating battery-less, wearable sensor devices using body heat energy harvesting.