IMEC recently announced a battery-free wireless 2-channel EEG system (electroencephalography or monitoring of brain waves) powered by a hybrid power supply using body heat and ambient light. The hybrid power supply combines a thermoelectric generator that uses the heat dissipated from a person's temples and silicon photovoltaic cells. The entire system is wearable and integrated into a device resembling headphones. The system can provide more than 1mW on average indoor, which is more than enough for the targeted application.
This is a brilliant idea, not only for its unique wireless headphone shape which provides patients more autonomy, but also the battery-free structure. As a matter of fact, it is driven by our body heat and plus, with the help of solar panels, to get some extra juice from ambient light.