Smartphones, MP3 players, heart rate monitors: a growing number of electronic companions are making our everyday lives easier. But as useful as these smart helpers may be, their constant hunger for power is a problem. One possible solution is to power them using the body's own kinetic energy. Researchers at the Karlsruhe Institute of Technology (KIT) are working on this.

Mini power station in the shoe

An important criterion is that the generation of electricity does not require any additional effort from the user. Medical scientist Christian Pylatiuk from the Institute for Applied Informatics (IAI) and his team have developed two systems based on this requirement. One design for the feet uses the body's weight when walking. A small cushion filled with fluid is placed under the heel and ball of the foot. When stepping and rolling, oil is pumped back and forth through a hose connection between them and drives a piston, which in turn drives a generator. The mini-electricity unit is currently installed in a prosthetic foot fitted with sensors, which actively supports the wearer's movements.

Moving with the times

Another generator can be worn on the arm like a watch. The difficulty here: In order to operate a generator, the very unsteady arm movements must be converted into a smooth movement. Pylatiuk has used a tried and tested technique for this. In contrast to the movement of an automatic watch, where the energy is stored by means of an oscillating weight tensioned by a spring, an induction motor is active here, in which an eccentric moves a magnet back and forth in a coil. However, the maximum output of 2.2 milliwatts is not yet sufficient to operate a hearing aid or charge a smartphone, for example. However, the KIT researchers expect improved results by the end of the year.

Expo 2017

Both devices are currently on display in the "Kinetic Lab" of the Museum for Energy of the Future at the Expo 2017 world exhibition, which is taking place in the Kazakh capital Astana until September 10. In addition to KIT, companies such as Samsung, Siemens and BMW are also represented there. This year's world exhibition is dedicated entirely to the topic of energy of the future. The topic area covers renewable energies, global warming and global energy supply.