The group describes the technology in Applied Physics Letters, from AIP Publishing. An energy harvester is attached to the wearer's knee and can generate 1.6 microwatts of power while the wearer walks without any increase in effort. The energy is enough to power small electronics like health monitoring equipment and GPS devices.
"Self-powered GPS devices will attract the attention of climbers and mountaineers," said author Wei-Hsin Liao, professor in the department of mechanical and automation engineering.
The researchers used a special smart macrofiber material, which generates energy from any sort of bending it experiences, to create a slider-crank mechanism -- similar to what drives a motor. The authors chose to attach the device to the knee due to the knee joint's large range of motion, compared to most other human joints. "These harvesters can harvest energy directly from large deformations," Liao said.
Due to the continuous back-and-forth the material will encounter when the wearer walks, every time the knee flexes, the device bends and generates electricity. This means the harvester can "capture biomechanical energy through the natural motion of the human knee," according to Liao. Previous wearable energy harvesters took advantage of the vibration caused in the device as a result of motion, which comes with drawbacks regarding efficiency.
"The frequency of human walking is quite slow, which significantly decreases the energy-harvesting capability," Liao said. Because the group's device uses a different method, it bypasses this limitation.
The prototype weighs only 307 grams (0.68 pounds) and was tested on human subjects walking at speeds from 2 to 6.5 kilometers per hour (about 1 to 4 miles per hour). The researchers compared the wearers' breathing patterns with and without the device and determined that the energy required to walk was unchanged, meaning that the device is generating power at no cost to the human.
[...] The article, "Macro fiber composite-based energy harvester for human knee," is authored by Fei Gao, Gaoyu Liu, Brendon Lik Hang Chung, Hugo H. Chan and Wei-Hsin Liao. The article appeared in Applied Physics Letters on July 16, 2019 (DOI: 10.1063/1.5098962) and can be accessed at http://aip.scitation.org/doi/full/10.1063/1.5098962.
(Score: 3, Informative) by Runaway1956 on Sunday July 21 2019, @12:25PM (2 children)
If you can put it in the heel of my boot, I'll think about it.
(Score: 1) by fustakrakich on Sunday July 21 2019, @07:43PM (1 child)
Maybe it's made for people who have no feet. Obviously you could get more energy by putting some piezo compressy thingy in a pair of sandals.
La politica e i criminali sono la stessa cosa..
(Score: 2) by FatPhil on Sunday July 21 2019, @10:43PM
Or - a hundred if they're watch batteries.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 3, Insightful) by The Mighty Buzzard on Sunday July 21 2019, @12:48PM (11 children)
Sorry, that's not how physics works. Without any noticeable increase, maybe, but as stated it's wrong.
My rights don't end where your fear begins.
(Score: 2) by fyngyrz on Sunday July 21 2019, @01:08PM (3 children)
Agreed.
First of all, moving mass through distance — doing work — takes energy. The device is not massless. Therefore, it takes work to move; and that requires energy. Secondly, it takes energy to bend the material in question; there will be some resistance to bending, and also, that mass is being moved through its own, independent distance by the motion of the knee joint.
What the conclusion is here is that the method used to measure the wearer's energy output was not sophisticated enough to tell the difference between device and non-device movement.
--
Ignorance is weakness.
(Score: 3, Interesting) by Anonymous Coward on Sunday July 21 2019, @02:15PM (2 children)
Slight variation -- what if this device took the same amount of energy to flex as the blue jeans that were worn by the control group? Then the energy required would be the same, just that with the device you harvest a tiny bit (instead of the extremely slight heating of the jeans due to flexing).
Clothing does waste some energy, compare to the nice sense of freedom when walking around naked!
(Score: 1, Funny) by Anonymous Coward on Sunday July 21 2019, @04:50PM
> Clothing does waste some energy, compare to the nice sense of freedom when walking around naked!
I tried that. The police came. I don't have a sense of freedom anymore. :(
(Score: 0) by Anonymous Coward on Sunday July 21 2019, @06:36PM
Just try short-shorts. You'll already get a huge improvement.
(Score: 2) by HiThere on Sunday July 21 2019, @04:08PM (1 child)
Not clear. If it only extracted energy on the downhill (compression) cycle, it might actually help. OTOH, an optimally "designed for walking" knee would already be extracting that energy. Kangaroos do it, but humans are recently apes living in trees, so they might not have that optimization.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 0) by Anonymous Coward on Monday July 22 2019, @06:32AM
AFAIK penguins have the most energy efficient walk, they wobble around. Just not going to catch any prey or escape a predator that way. But they do it because their enemy is the winter cold at Antarctica and they catch fish while swimming, not walking.
(Score: 2) by JoeMerchant on Sunday July 21 2019, @04:18PM (1 child)
I'm going to notice the #$)*( thing when it's just sitting there attached to me, much more so as I walk and it tugs at my skin and/or prevents my sweat from evaporating at the interfaces.
I may not notice the effort required to bend it, but it will take strong glue to keep me from unconsciously clawing it off of my body.
🌻🌻 [google.com]
(Score: 2) by JoeMerchant on Sunday July 21 2019, @06:40PM
Above was written before 1.6 microwatts was processed.... yeah, 1.6 microwatts, weighs 300gm, um... who cares?
A 1cm x 1cm solar cell should be good for 16 milliwats in full sun (a full 1m x 1m solar panel nets 160W), 1/1000th of that?
TFS should have lead with something from the vanishing significance dept.
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Sunday July 21 2019, @06:16PM (1 child)
So this device will not work for goose-stepping fascists but the heel device would.
(Score: 2) by The Mighty Buzzard on Monday July 22 2019, @10:48AM
Antifa will be crushed. They were going to start ironically goose-stepping next week. Wile missing the irony that they really are fascists, of course.
My rights don't end where your fear begins.
(Score: 0) by Anonymous Coward on Sunday July 21 2019, @08:25PM
They'd be better off trying to harvest boob kinetic energy. The main downside is that they wouldn't bounce so much.
(Score: 2) by takyon on Sunday July 21 2019, @12:49PM
Cheap, passive exoskeletons and limb attachments. [soylentnews.org]
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by legont on Sunday July 21 2019, @01:42PM (3 children)
300 grams "at no cost to the human"? They measured it, right?
Yeah, climbers will take it all right; up to their arses.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 3, Interesting) by RamiK on Sunday July 21 2019, @02:01PM (2 children)
Being a macrofiber likely means it's designed to substitute the pants' knee area so as long as it weights about the same as jeans inch-for-inch and doesn't introduce significant resistance, it won't matter.
compiling...
(Score: 2) by JoeMerchant on Sunday July 21 2019, @04:24PM
The reason it doesn't generate significant resistance is because it doesn't generate significant power.
Ordinary pants take more than 1.6 microwatts to deform while you're walking, not a shock that you could extract that much power from bending piezo elements, or whatever they're using.
We looked at "zero power" solutions for implantable device sensors - one I developed a small way was a piezo element that could wake the microprocessor when the patient "taps" on the device - the tapping motion would cause a flex in the piezo (springboard with a weight on the end arrangement), which created enough voltage to trigger a wakeup of the MSP430. When not being activated: zero power draw. There wasn't enough potential energy in the piezo springboards of ~2004 to make it worthwhile trying to extract operation energy from them while encased inside a titanium shell, but if that same piezo material was applied across a joint like the knee, it certainly could light LEDs while you walk.
🌻🌻 [google.com]
(Score: 2) by legont on Sunday July 21 2019, @05:01PM
Yeah, mountaineers climb wearing jeans.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 4, Touché) by Booga1 on Sunday July 21 2019, @01:44PM (3 children)
Weighs .68 lbs and only provides 1.6 microwatts? Why bother when you can use a 0.102oz(2.9g) coin cell battery in it with 220mAh capacity and get about 1375 hours run time at that kind of power usage?
This thing weighs too much and is too big to haul around for a "self-powered GPS device." Something tells me this professor has never actually gone climbing or mountain hiking, nor even talked to anyone who does those things. Otherwise they would have told him it was a no-go right away.
(Score: 1, Touché) by Anonymous Coward on Sunday July 21 2019, @02:18PM (1 child)
Hey, it's a prototype, give them a little benefit of the doubt. Stuff in real production is often much better than the initial proof of concept test samples.
(Score: 2) by legont on Sunday July 21 2019, @05:04PM
I am not saying it has no future use. What I am saying is that they faked the measurements pure and simple and were not even smart to hide it well.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 3, Interesting) by JoeMerchant on Sunday July 21 2019, @04:28PM
Something tells me this professor got some kind of grant to investigate "zero power" devices and this is the best he could come up with. Not any more impressive than the piezo films I worked with 15 years ago, though his form factor is a little more convenient.
As you say, a primary cell gives orders of magnitude more bang for your volume, weight, and buck, and by the time the primary cell has run down, the generative device may well have failed due to the harsh environment it is required to endure to capture its power.
🌻🌻 [google.com]
(Score: 2) by shortscreen on Sunday July 21 2019, @04:17PM (2 children)
This was on the green site years ago. I'd post a link except search engines are useless these days.
(Score: 2) by janrinok on Sunday July 21 2019, @05:59PM (1 child)
The idea may have been around for decades but this is a new device and the story was only released on 17.07.2019. It is not a dupe.
From TFA:
(Score: 0) by Anonymous Coward on Monday July 22 2019, @06:35AM
A reader of 'the green site' is a dupe.
(Score: 0) by Anonymous Coward on Sunday July 21 2019, @04:28PM
there may be unintended side effects of increased knee wear and tear leading to higher medical costs
(Score: 3, Insightful) by istartedi on Sunday July 21 2019, @04:31PM (5 children)
I can't imagine any doctor would recommend attaching a device to a joint, such that you'd have to make more effort to move it unless that device had some benefit such as stabilizing the joint. I was on a hike yesterday and got a little knee pain. I don't have any serious knee problem. Knees are just finicky. It's one of the last joints I'd want to play around with unless a doctor recommended something.
Run away from this thing, while you still can.
Appended to the end of comments you post. Max: 120 chars.
(Score: 2) by ilPapa on Sunday July 21 2019, @06:00PM (3 children)
My knees are still in pretty good shape, but after going on 4 decades of martial arts, I'm very protective of them. I've seen too many men my age who've gone through knee surgery after some Saturday afternoon beer-soaked softball or getting in their heads that they can still run that 10k after not having gotten off the sofa for years.
Yes, knees are the last joint you wanna be messing with.
You are still welcome on my lawn.
(Score: 2) by JoeMerchant on Sunday July 21 2019, @06:30PM (2 children)
My knees have been on borrowed time for 10+ years...
However: 1.6 microwatts? your knees literally put more effort into bending and unbending a pair of khaki pants.
Solar panels give ~160 W per square meter, so this knee power extraction scheme is competing with 1/100,000,000 square meter of solar panel, or a solar panel 1/10th of a mm on a side.
🌻🌻 [google.com]
(Score: 3, Funny) by ilPapa on Sunday July 21 2019, @09:11PM (1 child)
If you wanna generate some power from a joint, I got one right here, know what I mean?
You are still welcome on my lawn.
(Score: 2) by JoeMerchant on Monday July 22 2019, @01:55AM
1.6mW isn't even enough to spark... if you know what I mean.
🌻🌻 [google.com]
(Score: 3, Interesting) by JoeMerchant on Sunday July 21 2019, @06:34PM
Better still, use a solar cell. A solar cell 1cm x 1cm should weigh far less than 300gm, and produce 160/10000 W, or about 16 milliwatts in full sun: about 1000x the power proposed to be extracted by our ivory tower academian in his seminal paper on the subject (I assume nobody else was desperate enough to publish something so trivial.)
🌻🌻 [google.com]