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Wearable Device Generates Electricity From Walking Knee Movements
Zothecula writes "If you've ever worn a knee brace, then you may have noticed what a large change in angle your knee goes through with every step you take, and how quickly it does so. A team of scientists from the U.K.'s Cranfield University, University of Liverpool and University of Salford certainly noticed, and decided that all that movement should be put to use. The result is a wearable piezoelectric device that converts knee movement into electricity, which could in turn be used to power gadgets such as heart rate monitors, pedometers and accelerometers."
It could be used to power a truly awesome joy buzzer.
You could even use the power generated by your knees to travel from one place to another!
Apache guy, Open Source enthusiast, runner
Finally, a way to power our future borg implants.
Except that we already had this technology in 2008. And /. user Promatrax161 called out the idea in 2005. But then he may have adapted it from a shoe based version in 2001.
I'm willing to go out on a knee here (sorry) and declare this experiment a failure. They have generated 2 milliwatts. Milliwatts -- my spellchecker doesn't even recognize that. For $15, I could get a 1,000 milliwatt solarpanel, tape it to my dang knee, and just sit there. Peizoelectric tech has amazing applications, but this one appears to be a dud.
I was thinking more along the lines of the stillsuit, which if I recall correctly was powered in via movement.
Sex Power!
Well, since this is /. you're talking about something that mounts to one wrist.
Walking is a very low-energy form of movement that relies on some highly evolved bio-mechnics. Attempting to harvest a useful amount of energy introduces dissipation in parts of the 'mechanism' that have not evolved to handle it. The result can be anything from mild discomfort to quite serious injuries. So, such techniques are limited to a few mW, and are in most respects inferior to using a battery.
It's been years since I saw a bicycle with a dynamo on it for similar reasons.
...wearing that through a TSA checkpoint and onto a plane.
It must have been something you assimilated. . . .
I used to generate electricity like you, but then I took an arrow to the knee.
You are correct.
"It's basically a micro-sandwich -- a high-efficiency filter and heat-exchange system. The skin-contact layer's porous. Perspiration passes through it, having cooled the body ... near-normal evaporation process. The next two layers . . . include heat exchange filaments and salt precipitators. Salt's reclaimed. Motions of the body, especially breathing and some osmotic action provide the pumping force. Reclaimed water circulates to catchpockets from which you draw it through this tube in the clip at your neck... Urine and feces are processed in the thigh pads. In the open desert, you wear this filter across your face, this tube in the nostrils with these plugs to ensure a tight fit. Breathe in through the mouth filter, out through the nose tube. With a Fremen suit in good working order, you won't lose more than a thimbleful of moisture a day..."
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Sweat cools because the phase transition from liquid to vapor absorbs a lot of energy to break the bonds. This energy is provided by the skin, so as a result, the skin gets cooler. Likewise, if you condense the vapor back into a liquid, the exact same amount of energy is released again. If that condensation happens inside the suit, the suit will get warm, defeating the purpose of sweating in the first place. It would be like running in the desert in a raincoat.