It can be very tough to keep your gadgets charged up and ready to work or play all day if you aren’t near an outlet. There are several solar chargers and portable battery packs out there but those aren’t ideal in all situations. A team of researchers are working on a very novel way to charge your gadgets while you walk around in the form of a pair of shoes that have energy harvesting technology inside.
“Human walking carries a lot of energy,” says professor of mechanical engineering at the University of Wisconsin-Madison, Tom Krupenkin. “Theoretical estimates show that it can produce up to 10 watts per shoe, and that energy is just wasted as heat. A total of 20 watts from walking is not a small thing, especially compared to the power requirements of the majority of modern mobile devices.”
The team has been working to develop new method of converting mechanical energy into electrical energy that would work for generating power from a human walker. The process the team is working on now is known as reverse electrowetting. This technique uses a conductive liquid that works with a nanofilm-coated surface that is able to produce electricity.
The catch so far is that this process needs a high frequency, a higher frequency than is produced by people in motion. To remedy that problem the team combined electrowetting with a device called a bubbler. A bubbler has no moving parts and uses a pair of flat plates with a conductive liquid between them. The tiny holes in the bottom plate allow pressurized gas to enter and form tiny bubbles.
Those bubbles get larger, make contact with the top plate, and burst. By rapidly making these bubbles, which quickly burst, the conductive fluid moves back and forth to generate electricity. This method produces around 10 watts per square meter of surface and in the space of a shoe; the team believes that making 10 kW of power might be possible.