trainers charger

These trainers charge your smartphone while you walk

These smart shoes could be the answer though, as boffins at the University of Wisconsin-Madison have developed a pair of trainers capable of recharging your phone as you walk.

Dubbed InStep NanoPower, the new "bubbler" tech makes use of the kinetic energy generated by repeatedly putting one foot in front of the other.

The shoes use a high-tech sole fitted with a pair of flat plates separated by a small gap filled with a conductive liquid.