Nanowires Allow For Electricity-Generating Clothing

lee1 writes "The latest development in the field of 'energy harvesting', which includes such opportunistic technology such as self-winding watches, generators implanted in soldier's boots, and knee brace dynamos, is a cloth that generates electrical power. The cloth is newly developed by scientists in the US, and can produce up to 80 milliwatts per square metre. It is made from brush-like fibres composed of a Kevlar stalk surrounded by zinc oxide nanowire crystals that generate electricity through the piezoelectric effect. They can be grown on any substrate, including hair. The power harnessed from this effect could be used for anything from cosmetic components to the powering of medical devices."

Re:forgive my ignorance

[KublaiKhan]

Not necessarily. You waste a lot of energy moving your clothing around as-is; the fabric would likely be a little stiffer, but that's probably about it--they're not making the whole thing out of kevlar, apparently.

Re:Self-winding watches

[InterGuru]

Self winding watches do take extra energy. Every time you move your wrist you expend energy to set the winding mechanism going.

The amount of energy is so small as to be trivial and unnoticeable.

I suspect that 80 milliwatt per square meter is also unnoticeable, as we expend several hundred watts in ordinary motion.

When we worship philosophers, simply because they are philosophers, and denigrate plumbers simply because they are plumbers, we will soon find that neither our theories nor our pipes hold water.

Re:forgive my ignorance

[orclevegam]

Wouldn't harnessing this energy make the material harder to move in?

Actually, in the case of the knee-brace generator it makes it easier to move. The knee-brace has a clutch mechanism that only engages on the absorption portion of the step (when your knee is flexing to absorb the impact and transfer your weight) so the resistance of the brace actually helps your legs absorb the impact of stepping. The only problem with the current model is that it's rather bulky and heavy so until it's made lighter it makes it harder to move just from the weight of it. There are lots of ways this could be used to actually improve efficiency (much like active-braking generators in cars) rather than decrease it. Remember, all friction heat and to a lesser extent gravity (falling down a gravity well) is wasted energy, recapturing as much as possible helps cut down on entropy.

Re:Nano-generation Decision Point

[orclevegam]

Knee braces and such, though, break that model, because you have to do more physical work to generate the power.

Another article talks more about the knee-brace. It actually helps you walk because it's got a clutch that only engages when your knee is flexing to absorb shock. It adds zero (more or less) resistance when lifting and adds resistance when bracing, so you end up recapturing a lot of the energy wasted on the down step. It's really the same principle as the active-braking systems in electric cars that allow them to recapture a lot of the energy used in accelerating the car when it's braking.