The shorts and sleeping bag thatmean you’ll neverrun out of mobile battery again - because they're powered by your body heat *.Smart materials in the Power Shorts use kinetic energy created by the wearer's movements to charge mobile phones *.Modules attached to the fabric of the Recharge Sleeping Bagcapture thermal energy from a sleeper's body to create an electric charge *.Products have been developed by Vodafoneand Southampton University

Festival goers need never run out of phone battery again thanks to a new range of denim shorts and sleeping bags thatuse body heat and movement to generate electricity. The Power Shorts and Recharge Sleeping Bag can charge a phone's battery by harvesting energy from the human body using kinetic and thermoelectric technology. The wearable phone chargershave been designed by mobilephone company Vodafone withhelp from the University of Southampton.HOW DO POWER SHORTS WORK? The shorts are fitted with a phone connector and ferroelectret materials. As the wearer moves, the shorts gather kinetic energywhen these ferroelectret materials are squashed or deformed. The surfaces of these voidsare permanently charged. As the size and shape of thevoids in the shorts changes,a charge is produced on the surface of the material. The Recharge Sleeping Bag harvests thermal energy using the 'Seebeck Effect'. This effect is a process that produces an electrical charge causes by the changes in temperature of a thermoelectric module. These modules are printed on the fabric of the sleeping bag. The Power Shorts are fitted with foam-like ferroelectret materials.As the wearer moves, the shorts gather kinetic energy when these ferroelectret materials are squashed or deformed. These foam-like materials contain voids. The surfaces of these voids are permanently charged and exhibitpiezoelectric and pyroelectric properties. The word piezoelectricity means electricity resulting from pressure. When pressure is applied to the materials in the shorts they generate an electric charge. As the size and shape of the voids in the shorts changes this creates the electricity needed to charge the phone attached to the shorts by a connector inside the Power Pocket. The Recharge Sleeping Bag harvests thermal energy using the 'Seebeck Effect'. This effect creates pyroelectricity, which is theability of certain materials to generate a temporary charge when they are heated up or cooled down. In the case of the sleeping bag, this process monitors thechange of temperature through a thermoelectric module fitted to the fabric of the bag. Heat from the sleeper's body flows through this module contained within a multi-layered 'power felt'. This felt contains polymer films and two semi conductors that generate an electric charge as they heat up.