A group of American scientists presented a compact charger that works at the human body heat.
The new device, a miniature thermoelectric generator, is fully recyclable, flexible and does not require mains power. The power of the device is enough to charge a watch or a fitness bracelet; when walking fast, the device generates about 5 volts of electricity.
The prototype device, which is attached to the finger or wrist, is used in two forms (ring and bracelet).