Pulse Oximeter Fully Powered by Human Body Heat

The realization of a body-area network demands innovative solutions to efficiently power the wireless sensor nodes that typically consume about 100µW of power. Thermoelectric generators (TEGs) harvesting energy from wasted human body heat provide an attractive solution, potentially producing about 30µW per square centimeter of human skin. As a proof of concept, a wireless pulse oximeter has been developed that is fully powered by a watch-style TEG using commercial BiTe thermopiles. For a 15 seconds measurement interval, approximately 89µW of power is required from the generator, safely within the available 100µW power budget. The wireless pulse oximeter therefore achieves full energy autonomy. From a performance/cost perspective, superior results are expected from TEGs made up of MEMS thermopiles which are currently under development.