Researchers at the University of Wisconsin-Madison, United States, have developed a microfluidics technique that is able to scavenge considerably more energy than previous attempts from human footfalls, and convert it into electric power. The new approach could lead to a shoe-mounted generator that produces up to 10 watts, up from other attempts that yielded less than a watt. Tom Krupenkin, a mechanical engineering professor, said, “A lot of energy is simply wasted as heat while we walk. If one can convert this into electrical energy, numbers come out to be up to 10 watts per foot.” Devices such as cell phones and smart phones need about 1 to 2 watts, while small laptops need 10 to 12. The concept developed by the researchers involves microscopic droplets of conductive fluid flowing between electrodes coated with dielectric films. An electric current is produced when the area of overlap between the droplets and electrodes changes. Andrew Haughian, a partner at the Canada-based venture capital firm Pangaea Ventures, which is evaluating the technology for potential investment, said, “It’s a unique approach to energy harvesting. The biggest opportunity I see would be in [developing countries], where the power grid is not reliable.” Purchasing your own pair of power-generating shoes is still a long way off, however. A startup company, InStep NanoPower, has been established by Krupenkin and his colleagues. They have a first generation prototype device, and expect that the third generation harvester could be embedded in footwear. “This type of product will have to be a collaborative project between Instep and a shoe manufacturer,” Krupenkin says. “We can’t expect anything on the market earlier than two years.”
http://www.technologyreview.com/energy/38469/