The Power Pocket shorts from Vodafone will charge a smartphone for four hours

The Power Pocket shorts from Vodafone will charge a smartphone for four hours

Telecoms company Vodafone is trialling shorts and sleeping bags that use body heat to charge electrical gadgets like mobile phones or tablets.

Thermoelectric materials are printed with pairs of thermocouples and stitched into the garments, with the thermocouples then connected to make a thermoelectric module.

"One side of that is cold and the other is hot, and when you get a flow of heat through it you can create a voltage and a current. Voltage and current together equals electrical power," said Stephen Beeby, Professor of Electronic Systems at the University of Southampton, which helped develop the smart materials.

The wearer's body provides the heat on the inside layer, and its the difference between that temperature and the colder one on the outside that generates the power.

Vodafone said it will be trialling the Power Pockets and the Recharge sleeping bag through the festival season this summer.

"Eight hours in the sleeping bag, roughly speaking, will provide 24 minutes of talk time and 11 hours of standby time. That's assuming the inside of the sleeping bag is 37 degrees - human body temperature," said Beeby.

A full day of walking and dancing in the power pocket shorts will charge a smartphone for four hours.