 The electronics company Philips and Hull University also took part in the project.DARPA (Defense Advanced Research Projects Agency) of the United States pioneered research into the field of energy harvesting from vibrations, wanting to reduce the use of heavy rechargeable batteries that power communication devices carried by soldiers into battlefields.Most of the research was spent in development of "heel-strike" generators, powered by the pumping motion of a footstep, which would be embedded within a heel of an army boot.