Shoe Power That Can Walk the Walk

Shoes are already magical--they can light up, sprout wheels, and tone your thighs. Now an assistant professor of electrical engineering at Louisiana Tech University is taking them to the next step with a viable design for shoes that can power sensors and tiny devices. For real.

Ville Kaajakari developed a shoe concept that has a small generator in the sole to harvest energy. A couple of years ago I saw a similar idea during MoMA's Design and the Elastic Mind exhibit. Emili Padros' "Nonstop Shoes" would gather energy while you walk but his design was entirely conceptual. It looks like Kaajakari has the technology to make a real version.

Power from materials that produce currents under pressure is called "piezoelectric." Harvesting that energy has been a challenge, though. In an article published in MEMS Investor Journal, Kaajakari writes that his group's shoe power generator is "based on a low-cost polymer transducer with metallized surfaces for electrical contact." This differs from conventional ceramic transducers, he explains, because the plastic-based generator is soft and matches the shoe material, making it ideal to replace heel shock absorbers. New voltage regulation circuits developed at the university can then efficiently convert the charge into a usable voltage--2 milliwatts per shoe on average during a regular walk. Small, but potentially crucial.

The most advantageous part of this design for me is its potential to help isolated hikers and travelers in case of an emergency. Kaajakari has said that he thinks these shoes could provide enough power for location devices, charging up GPS receivers and radio-frequency transponders. One day Kaajakari would like the shoes to be able to power a cell phone.

Piezoelectric power is everywhere at the moment. The Washington Post reports that there are a bunch of recently piezoelectric power developments, including a Nokia patent for a device that charges your phone whenever it gets moved around. Plus, as Eric Bland recently reported, Georgia Tech scientists just created the world's first device that relies entirely on piezoelectric power. If you need off-grid power in a pinch, grabbing a shoe could be far easier than a hand-crank.

Image: Ville Kaajakari's design for a shoe power generator. Credit: Louisiana Tech University.