Characterization of Human Body-Based Thermal and Vibration Energy Harvesting for Wearable Devices

Abstract

Energy harvesting is an important enabling technology necessary to unleash the next shift in mm-scale and μW power computing devices, especially for wireless sensor nodes. Energy harvesting could play an important role in biomedical devices where it extends the lifetime of the system. Furthermore, it eliminates the need for periodic maintenance such as exchanging or recharging the battery. This paper presents experimental results of thermal and vibration energy harvested from human body using the thermoelectric generator and the piezo electric harvester, respectively. Contemporary research revealed that most of the published data, including harvesters datasheets, are adjusted for industrial or laboratory-setting environment. This paper focuses on obtaining experimental data from the human body using off-the-shelf harvesters, and discrete electrical components. Our experimental results showed that for 9 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area of thermoelectric generator, up to 20 μW of power can be generated at 22 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C room temperature. In addition, 0.5 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> piezo electric harvester can generate up to 3.7 μW when running at 7 mi/h. These data correspond to a power density of 2.2 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 7.4 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> for thermoelectric generator and piezo electric harvester, respectively. As such, the harvested energy from thermal and vibration of human body could potentially power autonomous wearable and implantable devices.