Converting Body Movement Into Electricity

The British Scientists have built a novel device that can convert body movement into electricity capable of powering small gadgets such as GPS trackers. It was created by researchers from the Universities of Cranfield, Liverpool and Salford. Designed to be worn on the  knees, it harnesses the energy produced when one walks. It could be used by the military to reduce the numbering of heavy batteries-- each weighing upto 10 kg -- that soldiers carry on foot patrol.
         The "energy harvester" is based on so-called piezoelectric materials that have long been used for making sonar sensors and ultrasound scanners and have become the focus of energy generation research in recent years. The device features an outer ring which rotates as the knee moves. It is fixed with 72 plectra that in turns move four energy- generating arms called bimorphs attached  to an inner hub. The vibrations generating the electricity. At the moment, The piece can harvest about 2 milliwatts of power. However, the researchers believed that the power output could exceed 30 milliwatts with a few enhancement, enough to run the latest GPS tracking devices.