In-Ear Thermal Power Capability and Thermoelectric Energy Harvesting Approaches

Thermal energy harvesting in the earcanal is a promising solution to extend the battery life of hearing aids or cochlear implants. Our research, carried out with twelve participants, demonstrates that the ear canal wall can deliver up to 200 mW through heat conduction, using a liquid-filled earplug. We introduce a thermoelectric energy harvester specifically designed for this application and propose theoretical tools to optimize its performance. The prototype was tested under various conditions, harvesting $54 \mu \text{W}$ to $96 \mu \text{W}$, depending on external factors, which could provide up to $25 \%$ additional battery life to state-of-the-art cochlear implants. The theoretical models are experimentally validated and suggestions for improvements are made for the next generation of prototypes.