Generating electricity by walking or swinging your arms....

UK researchers create a wearable power harvester.  

(PHYSORG)- Battery-powered devices could soon be a thing of the past thanks to a group of UK researchers who have created a novel energy harvester to power some of the latest wearable gadgets.

By strapping the energy harvester to the knee joint, a user could power body-monitoring devices such as heart rate monitors, pedometers and accelerometers by simply walking and not have the worry of running out of power and replacing batteries. Soldiers may find this device particularly useful as they often have to carry up to 10kg of power equipment when on foot patrol.

The device has been presented today, 15 June, in Smart Materials and Structures journal by researchers from Cranfield University, The University of Liverpool and University of Salford.

The energy harvesting device, which is designed to fit onto the outside of the knee, is circular and consists of an outer ring and central hub. The outer ring rotates as the knee joint goes through a walking motion. The outer ring is fitted with 72 plectra which "pluck" four energy-generating arms attached to the inner hub.

As an individual plectrum deflects off one of the arms – which are called bimorphs – it causes it to vibrate, much like a guitar string, and generates the electrical energy.