motion powered energy harvester fits in shoe
aug 25, 2011
motion powered energy harvester fits in shoe


a device inserted into the soles of shoes may generate 2 watts of usable electricity from the wearer’s movements while walking,
using a technology being developed by a research team at the university of wisconsin-madison

led by tom krupenkin and j. ashley taylor, a team of microelectronics researchers at america’s university of wisconsin-madison
have developed a new energy-harvesting technology that utilizes the energy generated by human motion, in a way that is
hundreds of times more efficient than motion-powered piezo-electric systems. with their company instep nanopower,
the team hopes to produce a device that fits in the sole of a shoe and uses the reverse electrowetting process to generate
about two watts of usable electricity from the simple act of walking.


device prototype

humans, generally speaking, are very powerful energy-producing machines,‘ explains krupenkin,
professor of mechanical engineering. ‘while sprinting, a person can produce as much as a kilowatt of power,’
and up to 10 watts of power is lost as heat each time a foot hits the ground. the difficulty is in engineering
technology that efficiently converts mechanical to electrical energy on this scale.

the research team utilizes an innovative energy-harvesting technology called ‘reverse electrowetting’.
in electrowetting, a conductive liquid droplet, placed on an electrode, becomes physically deformed by an applied electric charge.
the process is based on the same principles of electrostatic capacitors, but involves the replacement of a physical electrode
with a electrically conductive liquid. in the reversed process used by the krupenkin, the changing physical form of the droplets
on dieletric-coated plates generates charge, which can be harvested as electrical power.

the energy generated increases in proportion to the number of droplets used. while the initial tests involved 150 droplets,
producing a few milliwatts of power, krupenkin expects that a device with 1000 droplets could generate up to 10 watts
while fitting in an area of 40 square centimeters (6.2 square inch).


left: water droplet on the nanostructured surface developed by the research team (note: the device uses mercury or a gallium-alloy to function, not water)
right: diagram of the functional basis of the technology, liquid microdroplets caught between electrode plates

the electricity generated can be used to directly power a range of mobile devices via physical connection to the microfluidic device;
or alternatively the harvester can be integrated with a wifi hot spot to reduce the power consumption of wireless devices,
increasing the duration of a battery charge by up to 10 times.

instep nanopower is working on a prototype device that fits into the sole of a shoe, capable of generating about two watts of power
and thus recharge a standard cell phone battery over the course of a two hour walk. a commercially ready device is expected within two years.

via nature

comments policy
LOG IN VIA
login with designboom
designboom's comment policy guidelines
generally speaking, if we publish something, it's because we're genuinely interested in the subject. we hope you'll share this interest and if you know even more about it, please share! our goal in the discussion threads is to have good conversation and we prefer constructive opinions. we and our readers have fun with entertaining ones. designboom welcomes alerts about typos, incorrect names, and the like.
the correction is at the discretion of the post editor and may not happen immediately.

what if you disagree with what we or another commenter has to say?
let's hear it! but please understand that offensive, inappropriate, or just plain annoying comments may be deleted or shortened.

- please do not make racist, sexist, anti-semitic, homophobic or otherwise offensive comments.
- please don't personally insult the writers or your fellow commenters.
- please avoid using offensive words, replacing a few letters with asterisks is not a valid workaround.
- please don't include your website or e-mail address in your comments for the purpose of self-promotion.
- please respect jury verdicts and do not discuss offensively on the competition results
(there is only one fist prize, and designboom usually asks renown professionals to help us to promote talent.
in addition to the awarded designs, we do feel that almost all deserve our attention, that is why we publish
the best 100-200 entries too.)

a link is allowed in comments as long as they add value in the form of information, images, humor, etc. (links to the front page of your personal blog or website are not okay). unwelcome links (to commercial products or services of others, offensive material etc. ) will be redacted. and, ... yes, spam gets banned. no, we do not post fake comments.

product library