Solar Backpack As a woman who loves sports, I've always found the concept ofbreasts bothersome. If all goes according to plan, they will fulfiltheir intended function for about three of the 70 years that I havethem. The rest of the time, they alternate between getting in myway and embarrassing me. They are a favourite target of Frisbeesand footballs. Finding sports bras is a chore. Shirts don't fit.
And these are just the physical discomforts. I am still tortured bythe memory of three cousins standing in a circle around me, at theimpressionable age of 10, mocking my early development and tellingme that I was going to be the Asian Dolly Parton. Fortunately, thatnever happened, but the possibility haunted my late childhood.
Then one day recently, I had an idea. As I rode a bus to theoffice, my messenger bag slung uncomfortably across my chest, Ithought, "Why not put the girls to work?" Human-powereddevices are showing up everywhere, from Rotterdam's sustainabledance floor to human-powered gyms in Hong Kong. The timing seemedperfect – perhaps even overdue – for a bra that couldharness the untapped power of breast motion.
The idea of an energy-generating bra isn't as crazy as it mightsound. The underwear company Triumph International Japan recentlyunveiled a solar-powered bra that supposedly will generate enoughenergy to power an iPod. But I live in foggy San Francisco andprefer not to walk around in my underwear in public. Could someonedesign an iPod-powering bra for me?
I decided to run the question past some scientists. It turns outthat the physics of breast motion has been studied closely for thelast two decades by a gamut of researchers – most of themwomen. LaJean Lawson, a former professor of exercise science atOregon State University, has been researching breast motion since1985 and now works as a consultant for companies such as Nike todevelop better sports-bra designs. Lawson is enthusiastic about myidea, but warns that it will be tricky to execute. You would needthe right breast size and the right material, she explains, and thebra itself would have to be cleverly designed. "It's just amatter of finding the sweet spot, between reducing motion to thepoint where it's comfortable but still allowing enough motion topower your iPod," she says.
Lawson explains that breasts move on three different axes: fromside to side, front to back, and up and down. The most motion isgenerated on the vertical axis. Naturally, the bigger the breast,the more momentum it generates. "Let's face it – ifyou're a double-A marathoner, you're probably not going to get thatiPod up and running," Lawson says. Measurements compiled byLawson and her colleagues show that a D-cup in a low-support bracan travel as much as 35 inches (89cm) up and down (35 inches!)during exercise, while a B-cup in a high-support bra barely movesan inch.
Fabric and design are also important factors in distance travelled.Elastic fabric allows the breast to move more. Choosing between anencapsulation design, in which the cups are separated, or acompression design, where they are hugged close to the body, canalso affect breast motion. An encapsulation design further reducesmotion because two smaller masses are easier to control than onelarge one. "Also, if you have a really high neckline, thebreasts won't fly up," Lawson says. So I am in the market foran elastic, compression-style bra with a low neckline. Sexy!
Of course, even a bra that perfectly maximises motion (withoutsacrificing support and comfort) would be useful to me only ifthere were a way to turn that motion into energy. For a primer onhow to do that, I turn to Professor Zhong Lin Wang of Georgia Tech,who is working to develop fabric made from nanowires that willcapture energy from motion. Wang's wires are about 1/1,000th thewidth of a human hair. When woven together in a fabric, thesenanowires rub up against one another and convert the mechanicalenergy from the friction into an electric charge. According toWang, the fabric is cheap to produce and surprisingly efficient;his team hopes to use it to create energy-generating T-shirts andother articles of clothing. A square metre of fibre produces about80 milliwatts of power, which is enough to run a small device suchas a mobile phone. Wang expects to have a shirt available forpurchase within five years.
Many bra patterns call for about a metre of fabric, which wouldprobably mean that a regular bra would have enough energy to poweran iPod. But the fabric could also be layered – doubling, oreven tripling, the amount of energy produced. I ask Wang whetherhis fabric could be used to make a bra. "Bras would beideal," he says. "There is a lot of friction and movementin that general area. And the fabric would be thick."
"So you can generate enough energy to power an iPod?" Iask.
"Definitely," Wang replies.
I ask Wang if this bra would be machine-washable.
"You don't need to wash a bra," he says.
I disagree. Wang says his team has been working on the washingproblem for a while. Nanowire technology can generate electricityonly if the space between the wires is maintained, and that spacemight be affected if the fabric were agitated by a regularwashing-machine. One solution would be to layer the fabric so thatthe parts that directly touch the skin could be washed, leaving thenanowires in between untouched.
There is one more approach I want to investigate, one that mightsupplement Wang's technology. Is there a way to capture the energyof the bra strap, which bears the pressure of holding up the breastmass? To answer this question, I call Larry Rome, a biologyprofessor at the University of Pennsylvania and the creator ofLightning Packs. The Lightning Pack, intended for long-haul hikersand for the military, generates kinetic energy from the verticaldisplacement of a heavy backpack. Would it be possible to use thekinetic energy generated from a breast's vertical displacement?
"The backpacks we've built are intended to carry between 40and 80 pounds," Rome says.
I cite the D-cup numbers given to me by Lawson. "Well, that'snot normal, is it?" Rome asks.
I reply that it probably isn't.
But after a moment's thought, Rome comes up with an idea. TheLightning Pack uses a rotary generator, which converts motion intoenergy by winding a rotor as the backpack moves up and down. Rotarygenerators produce up to 7 watts of energy, enough to power acompact fluorescent light bulb.
Rome says that it might be possible to insert a linear generatorinto the bra. A linear generator is a lot smaller and createsenergy by moving a piston up and down. Rome concedes that with theright body type, this just might work, though he warns that it"probably wouldn't be very comfortable".
Still, if someone were to engineer a kinetically powered bra, evenone that isn't quite as comfortable as the old-fashioned kind, I'dbe intrigued – and I might just start looking at my breastsin a different light. Maybe it's not very sexy to see breasts as apair of batteries, but oil prices are so high that people arejogging to work. It may be time for breasts to start pulling theirown weight.
Futuristic fashion
By Jamie Merrill
Self-cleaning underwear
Scientists working for the US military have used self-cleaningfabrics to create T-shirts and underwear that can be worn for weekswithout washing. The garments, which use nanoparticles andchemicals to repel water, oil and bacteria, cost £14m todevelop and have been licensed to Alexium Group in London forcivilian use. Available soon.
Kameraflage
Digital cameras see a broader spectrum of light than the naked eye,and these vests incorporate pigment that is normally invisible. Thetechnology's uses include billboards, fashion and cinema –Kameraflage can watermark video and filmed content, spoiling theefforts of would-be pirates intent on recording movies on the sly.
Solar-powered handbag
Engineering student Joe Hynek's handbag may not be the height ofstyle, but thanks to its solar panels it will charge your mobilephone, MP3 player or camera. "One problem with puttingtechnology in clothing is that it looks dorky," he says."My goal is to use solar cells in a way that'sunobtrusive." The handbag will hit the market at around£150.
His-and-hers LED jackets
Created by designer Barbara Layne, these his-and-hers coats, whichgo by the name of Jacket Antics, use embedded LEDs on their backsto send messages using scrolling words. They are even clever enoughto know when you are holding hands and will run the message acrossboth of your backs.
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