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Microchip Powered by Body Heat

CmdrTaco posted more than 6 years ago | from the i-couldn't-power-an-8088 dept.

Power 73

An anonymous reader writes "MIT and Texas Instruments researchers have designed a chip that they say could be up to 10 times more energy efficient than current technology. The chip's power consumption is so low that devices with the chip may even be able to be recharged using the owner's body heat." The intent is to use these in medical applications like pacemakers where one would expect to have the free power source.

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73 comments

Powered by heat? (3, Interesting)

Bazman (4849) | more than 6 years ago | (#22828632)

Two things spring to mind:

  1. If it's powered by your body heat, it's going to make you colder...

  2. Don't you need a temperature _gradient_ to get useful power out of heat?

Re:Powered by heat? (1)

Pinky's Brain (1158667) | more than 6 years ago | (#22828662)

I imagine heart muscle temperature is higher than blood temperature.

Re:Powered by heat? (0)

Anonymous Coward | more than 6 years ago | (#22828802)

TFA says "powered indefinitely by a person's body heat or motion". I guess that a pacemaker would be powered by motion.

Goatse (-1, Troll)

Anonymous Coward | more than 6 years ago | (#22828718)

Goatse. [twofo.co.uk] [goatse.ch]

You nerd faggots love it.

In other news, Zeus sucks the cock.

Re:Powered by heat? (0)

Anonymous Coward | more than 6 years ago | (#22828786)

Addressing point #1, yes. It will make your body a little colder, and as a result you'll have to feed a little more. So it's a device powered by food, which is still pretty good.

Re:Powered by heat? (3, Informative)

masshuu (1260516) | more than 6 years ago | (#22828804)

answer to number 1: No, about 60-70% of the energy we produce is heat energy. Much of it is excess that is lost through the skin. A small chip that doesn't need much power won't steal your body heat and make you cold.

Re:Powered by heat? (3, Insightful)

exploder (196936) | more than 6 years ago | (#22829308)

Parent is right--you might as well say that putting a teakettle on your gas range makes the flame get colder. It doesn't. It's just dissipating (part of) the heat through something useful instead of out into the environment at large.

Re:Powered by heat? (2, Interesting)

EaglemanBSA (950534) | more than 6 years ago | (#22828814)

1.) Yes, it will indeed take heat from your body, but it would do nothing more than force the heart to pump a little more blood to maintain your body temperature. Many people don't know that one of the many functions your cardiovascular system performs is temperature control - it's one of the world's most complex heat exchangers. You introduce a small enough cold sink, and it will heat that area of the body up to make up for it. 2.) That depends on how they're getting power from the heat - if it's powering a heat engine and runs off heat flux, then yes, they would need a temperature gradient (which isn't that hard to get anyhow - put the cold sink near the epidermis and the hot sink near your heart/brain/etc.). If they're using the heat to run a small chemical reaction, then no, they probably wouldn't need a temperature gradient (e.g.: when using two dissimilar metals to generate a charge, the absolute temperature is directly proportional to the reaction rate). I'm currently studying the thermodynamics of the body for my master's, it's a very interesting subject.

Re:Powered by heat? (1)

norton_I (64015) | more than 6 years ago | (#22829110)

(e.g.: when using two dissimilar metals to generate a charge, the absolute temperature is directly proportional to the reaction rate).


Thermopower from bimetalic contacts definitely requires a cold junction to generate power.

If you are talking about a consumable chemical reaction, then all you have is a battery. It is true that chemical reactions often go faster at elevated temperatures, but that is not the same thing.

Re:Powered by heat? (1)

promethean_spark (696560) | more than 6 years ago | (#22834782)

At super low power/voltage it may be possible to rectify thermal noise in a warm semiconductor and use it to power circuitry. There are probably other ways to harness heat without a thermal gradient too, heat is just motion at an atomic scale so if you can harness that motion for power you don't need a gradient, just like a windmill doesn't need a wind gradient to work. It would convert heat to energy and thus cool itself, but the human body produces about 100W and a medical device would use a small fraction of a watt. I doubt someone would have trouble with having to produce 0.001% more heat - a haircut is much more drastic in the heat loss department.

Re:Powered by heat? (1)

norton_I (64015) | more than 6 years ago | (#22835362)

Uh, no. You can't rectify thermal noise, at least not on a continuous basis. Thermal noise has zero power content -- that is what thermal noise means. The force is 90 degrees out of phase with the displacement so the average power is zero.

A wind turbine requires a temperature gradient to operate, which is what generates wind in the first place.

Please see the second law of thermodynamics, the first law of thermodynamics, and Maxwell's demon.

Re:Powered by heat? (1)

internic (453511) | more than 6 years ago | (#22833676)

That depends on how they're getting power from the heat - if it's powering a heat engine and runs off heat flux, then yes, they would need a temperature gradient (which isn't that hard to get anyhow - put the cold sink near the epidermis and the hot sink near your heart/brain/etc.). If they're using the heat to run a small chemical reaction, then no, they probably wouldn't need a temperature gradient (e.g.: when using two dissimilar metals to generate a charge, the absolute temperature is directly proportional to the reaction rate). I'm currently studying the thermodynamics of the body for my master's, it's a very interesting subject.

Hopefully, since you're studying thermodynamics, you're aware that there are only two options: 1) It's using up some finite internal resource (e.g., internal energy) or 2) it's working by moving heat from a hotter reservoir to a colder one. If it's doing the first, then it's similar to a (possibly very effective) battery. If it's not doing either 1 or 2, then it's directly violating the second law of thermodynamics. I think the point made by earlier posters is that if it's deep in the interior of the body near the heart, as suggested in the summary, one would expect there won't be much of a temperature gradient. And remember that the efficiency of a heat engine at deriving work decreases as the temperatures of the two heat reservoirs become similar [gsu.edu] .

Anthrogeneration (1)

Dr. Cody (554864) | more than 6 years ago | (#22828858)

In the current Dutch issue of "Scientific American," there's an article about body microgeneration.

One proposal is to use microscopic plates separated by orthogonally arranged nanotubes. Connected to one plate and touching small feelers on the other, they would function as a piezoelectric generator for exploiting ambient motion. The idea is to apply this to similar applications as in TFA.

As far as using body heat as an RTG [wikipedia.org] , the idea is of course to use the temperature gradient between the body and the ambient air.

Personally, I'm most interested in this tiny DC-DC converter they've got.

Re:Anthrogeneration (1)

Nairanvac (912343) | more than 6 years ago | (#22829418)

The Dutch Scientific American? Wouldn't that just be the Scientific Dutchman?

Re:Anthrogeneration (1)

Dr. Cody (554864) | more than 6 years ago | (#22829456)

Yeah, I know. When I saw it at the newsstand on vacation, I did a double-take and got a copy. The front page says "Scientific American - Nederlandstalig" ('in Dutch').

Re:Powered by heat? (1)

stands2reason (1260520) | more than 6 years ago | (#22828886)

Your first point is wrong; our understanding of thermodynamics doesn't let us make heat simply go away, because your second point is true. This chip would have to use a thermocouple and extract energy from the *flow* of heat. Which, I wouldn't expect there to be much of a gradient inside the body...

Re:Powered by heat? (3, Insightful)

MrNaz (730548) | more than 6 years ago | (#22828888)

1. Having skin exposed to anything less than 37oC makes you colder. Losing a few extra W of thermal energy to power a microchip will not make a difference, it's trivial compared to the amount of energy you lose just by being exposed to air.
2. No, chemical reactions that are endothermic will occur at any temperature that supplies the necessary activation energy to the physical reagents.

Hope I didn't sound like an elitist snob...

Re:Powered by heat? (1)

Fanro (130986) | more than 6 years ago | (#22829162)

2. No, chemical reactions that are endothermic will occur at any temperature that supplies the necessary activation energy to the physical reagents.
But unless you have a source of new reactants, and a place to dump your product, your reaction will soon reach chemical equilibrum.
Essentially that is a battery.

You really need some sort temperature gradient to convert body temperature into work. I do not see how a device inside the body could do that with any efficiency.

Re:Powered by heat? (1)

MrNaz (730548) | more than 6 years ago | (#22832594)

unless you have a source of new reactants, and a place to dump your product

What, you mean like the bloodstream, which supplied readily combustible sugar and carries away the products of glucose reactions?

Re:Powered by heat? (1)

Fanro (130986) | more than 6 years ago | (#22833112)

If you are using sugars from the blood as a power source (possible, but I think beyond current technology) then you are definitely not recharging by "using the owner's body heat", which was the point of this thread.

Beyond current technology... (1)

Slur (61510) | more than 6 years ago | (#22836310)

Good pun...

But actually, I don't see why someone hasn't developed an ATP (?) powered circuit! All you need is a cathode with an enzyme or catalyst that breaks apart sugars and steals their electrons, and any kind of anode. Given the current state of molecular engineering - and certainly cell tinkering - this should be almost easy!

Obviously this has already been buried by Big Oil, along with the Free Energy device, test-tube Cold Fusion, and the Perpetual Stirling Engine.

Re:Beyond current technology... (1)

Fanro (130986) | more than 6 years ago | (#22837660)

I do not think you would find ATP outside of a cell. IIRC ATP acts as a pain signal if found outside of cells, since that would indicate some ruptured membranes.
So this bot would have to drill into fresh cells and suck them out.

If it was not for the pain thing, and the difficulty in getting it into cells, I would market an ATP energy drink.
Guaranted to give you back energy instantly, whitout any sugars and fats!

Re:Powered by heat? (1)

allcoolnameswheretak (1102727) | more than 6 years ago | (#22829178)

>1. Having skin exposed to anything less than 37oC makes you colder. I think this is wrong. Having skin exposed at 37C would make you very hot. Your body produces excess heat that has to be expelled somehow. At 37 the environment wouldn't take any heat away from you so your body would start to sweat in an effort to get rid of the excess heat more efficiently.

Re:Powered by heat? (0)

Anonymous Coward | more than 6 years ago | (#22829260)

" GP still stands

Re:Powered by heat? (0)

Anonymous Coward | more than 6 years ago | (#22829310)

"
GP still stands

Slasdot html formatting is stupid

not being able to post a correction until 8 minutes later is more stupid "Slow down Cowboy(neal)!"

Re:Powered by heat? (0)

Anonymous Coward | more than 6 years ago | (#22829422)

" < 37 " =/= " <= 37 "
GP still stands
Slashdot html formatting is stupid
not being able to post a correction until 12 minutes later is more stupid "Slow down Cowboy(neal)!"

Re:Powered by heat? (1)

MrNaz (730548) | more than 6 years ago | (#22832624)

"I think this is wrong."
Then you think wrong. How you "feel" about the temperature is not relevant to the actual temperature. Furthermore, my point was that the body generates huge amounts of heat, the use of which will not affect the body adversely.

Re:Powered by heat? (1)

vertinox (846076) | more than 6 years ago | (#22828924)

1. If it's powered by your body heat, it's going to make you colder...

Considering how much of your body is devoted to getting rid of excess heat (skin and sweat glands) I don't see this as a bad thing.

2. Don't you need a temperature _gradient_ to get useful power out of heat?

It never hurts to exercise.

Re:Powered by heat? (1)

mikael (484) | more than 6 years ago | (#22830268)

1. If it's powered by your body heat, it's going to make you colder...

If you turn down the thermostat on your central heating it's going to make you colder... ... but your body will burn more calories to maintain core and extremity body temperature.

Re:Powered by heat? (1)

sempernoctis (1229258) | more than 6 years ago | (#22831054)

2. Don't you need a temperature _gradient_ to get useful power out of heat?
My physics is a bit rusty, but I could swear that generating power without a significant gradient violates the 2nd law of thermodynamics. OTOH, if they've figured this out, maybe we will have yet another patent in the works for a perpetual motion machine.

Re:Powered by heat? (1)

Pyrrus (97830) | more than 6 years ago | (#22833122)

It depends what you consider significant. According to Carnot's theorem, the efficiency of a heat engine is increases with the difference between the hot reservoir and the cold reservoir. So the difference between one's body temperature and ambient temperature isn't much, therefore efficiency is low, but power can still be produced.

Re:Powered by heat? (1)

sempernoctis (1229258) | more than 6 years ago | (#22836004)

That would work for a chip mounted somewhere on your body (as long as you stay someplace cold; no summer trips anywhere tropical for people that would depend on this), but for devices implanted in your body, like a pacemaker, wouldn't this still be a problem?

Re:Powered by heat? (1)

chanio (321367) | more than 6 years ago | (#22832828)

They surely got inspired with the animated film Matrix Renaisance. At least, there is now a reason to keep most of our race alive...

Implantable devices running off body heat? (1)

niceone (992278) | more than 6 years ago | (#22828636)

The article mentions implantable devices running off body heat - how would that work? I thought to harvest energy you needed a temperature difference, where would an implanted device get that?

Just wondering...

Re:Implantable devices running off body heat? (1)

protobion (870000) | more than 6 years ago | (#22828908)

The normal "core" body temperature is 37 deg C. Skin however, being exposed , is substantially cooler at 30 deg C when bare and exposed to ambient temperature. A 7 deg difference has been harvested for energy before using Low temperature differential sterling engines.

But i am a cold hearted bastard (5, Funny)

Timesprout (579035) | more than 6 years ago | (#22828644)

you insensitive clod!

Re:But i am a cold hearted bastard (1)

lyml (1200795) | more than 6 years ago | (#22828826)

It's cool, it works with difference in temperatures.

Oh wait cool, sorry about that didn't mean to be all cold.

Oh wait cold... I'll just shut up now...

Re:But i am a cold hearted bastard (0)

Anonymous Coward | more than 6 years ago | (#22829148)

and Jessica Alba can power an Aircraft-Carrier...

free power source? (0)

Anonymous Coward | more than 6 years ago | (#22828648)

free source? is it GPL of BSD licence?

Dupe! (5, Informative)

Clazzy (958719) | more than 6 years ago | (#22828650)

We [slashdot.org] know [slashdot.org] . It did seem like a familiar read.

Re:Dupe! (0)

Anonymous Coward | more than 6 years ago | (#22829592)

The 'matrix' tag seems apropos. There must be a glitch here.

It might work... (4, Funny)

hyades1 (1149581) | more than 6 years ago | (#22828674)

"The chip's power consumption is so low that devices with the chip may even be able to be recharged using the owner's body heat."

Except, probably, my ex. She'd have to to crawl up onto a rock and bask for a couple of hours before something like that would work for her.

Re:It might work... (0)

Anonymous Coward | more than 6 years ago | (#22828800)

As a guy who is in a 3 y.o. divorce proceedings on a 1 year marriage, I find that pretty funny.

Yeah (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#22828700)

But does it run Linux?

REPOST (0)

Anonymous Coward | more than 6 years ago | (#22828704)

Nice REPOST

Heat is the OPPOSITE of a power source (0)

Anonymous Coward | more than 6 years ago | (#22828806)

Heat is where all power goes, not where it comes from. A temperature gradient on the other hand...

cochlear implants ... (5, Interesting)

constantnormal (512494) | more than 6 years ago | (#22828810)

... would seem to be a much more likely implanted medical device than pacemakers to use this technology. Having a pair of fully-implanted, self-powered devices that independently provide sound to each ear would seem to be a huge step forward, and readily achievable with this sort of technology.

And with a generation rapidly driving themselves deaf via iPods, a technological solution like this would seem to be appropriate and is arriving just in time.

While I don't know what kind of voltages and currents a pacemaker uses to regulate heart activity, it would seem a lot more likely that a cochlear implant would use less. Plus, there's a lot less downside risk if the device malfunctions.

Re:cochlear implants ... (0)

Anonymous Coward | more than 6 years ago | (#22828972)

And with a generation rapidly driving themselves deaf via iPods, a technological solution like this would seem to be appropriate and is arriving just in time.


Acquaint yourself with the 1980s Sony Walkman, sir.

Re:cochlear implants ... (1)

ruinevil (852677) | more than 6 years ago | (#22829016)

Plus, there's a lot less downside risk if the device malfunctions.


Until the device (probably the battery) explodes in your skull.

Re:cochlear implants ... (2, Funny)

gomiam (587421) | more than 6 years ago | (#22829368)

Until the device (probably the battery) explodes in your skull.

... and its residue mixes with your brain (whatever was left) and makes you search for spare parts (braaaaiiiiinnnnssss...).

Re:cochlear implants ... (0)

Anonymous Coward | more than 6 years ago | (#22829462)

I agree because a pacemaker isn't power hungry due to the chip, it's power hungry due to the jolt (technical word) of electricity it must provide to the heart to make pace. This far exceeds the energy consumption of the chip.

If medical implantables are the goal, there are better applications where the current on the chip begins to dominate.

Re:cochlear implants ... (2, Interesting)

InterGuru (50986) | more than 6 years ago | (#22829910)

I have a pacemaker. The manufacturer ( St. Jude ) claims that the battery will last 6-8 years.

In the old days pacemakers used a plutonium powered thermoelectric battery. This lasted forever, or about 25,000 years to be precise. They are now banned in the US because of the danger that the plutonium could be released in some way, such as a plane crash, a gunshot wound, or crematorium . They actually had to dig up some bodies because the undertaker did not remove the battery.

Haven't we all seen this movie? (5, Funny)

Snarkhunter (1056150) | more than 6 years ago | (#22828820)

I think we have. Except that in the movies, the humans weren't dumb enough to TEACH the robots to feed of body heat. Oh well. I for one would like to offer our slightly peckish robotic overlords a light brunch.

Lord Kelvin to the Rescue (1)

internic (453511) | more than 6 years ago | (#22833694)

I think we have. Except that in the movies, the humans weren't dumb enough to TEACH the robots to feed of body heat. Oh well. I for one would like to offer our slightly peckish robotic overlords a light brunch.

Right, but unlike in that movie we have the laws of thermodynamics to protect us.

I love The Matrix, but science was not its strong point.

The logical next step. (0)

Anonymous Coward | more than 6 years ago | (#22829002)

Also perfect for powering RFID-enabled smart implants.

What is the Matrix? (1)

catmistake (814204) | more than 6 years ago | (#22829172)

Throughout human history, we have been dependent on machines to survive. Fate it seems is not without a sense of irony. The human body generates more bio-electricity than a 120-volt battery and over 25,000 BTU's of body heat. Combined with a form of fusion the machines have found all the energy they would ever need. There are fields, endless fields, where human beings are no longer born, we are grown. For the longest time I wouldn't believe it, and then I saw the fields with my own eyes. Watch them liquefy the dead so they could be fed intravenously to the living. And standing there, facing the pure horrifying precision, I came to realize the obviousness of the truth. What is the Matrix? Control. The Matrix is a computer generated dream world built to keep us under control in order to change a human being into this.

Masturbation power cell, here we come (1)

OMNIpotusCOM (1230884) | more than 6 years ago | (#22829410)

This is just one step closer to harnessing the incredible power generated by the hands (or finger, I guess... if that's your thing) of over-stimulated teenagers. I, for one, welcome our sticky overlords... I just won't shake their hands.

Re:Masturbation power cell, here we come (0)

Anonymous Coward | more than 6 years ago | (#22829650)

Who says it's limited to "teenagers"?

I'm 33 years old, and I'm still married to my right hand!

Best place for this device- (0)

Anonymous Coward | more than 6 years ago | (#22831128)

In the anus or vagina.

Not gonna fly, basic thermodynamics (1)

Ancient_Hacker (751168) | more than 6 years ago | (#22833092)

I wish reporters had to take a class in basic science.

You can't effectively harvest body heat. The efficiency of any heat engine is proportional to the temperature drop, in absolute degrees. The internal body temperature gradient is unlikely to be much more than a degree Farenheit. So any heat engine in the body is limited to an absolute best efficiency of under a quarter of a percent. And you'd have to find some working fluid that changes phase across that temperature range. Not very likely. You could do a thousand times better harnessing the heatbeat energy with a microphone. And even that's ridiculous.

Re:Not gonna fly, basic thermodynamics (1)

VanessaE (970834) | more than 6 years ago | (#22834030)

Who's to say that one couldn't design a large version of this chip (or something remotely similar), and implant it just under the skin? You'd want to put it somewhere on/in the patient's upper back, neck, just under the scalp, or anywhere else that is naturally warm and at the same time, usually exposed to the ambient air. Seems to me that would be the easiest way to get a fairly large gradient, especially on a cool day.


The same should hold true for the lower legs - the body surely has to expend at least some energy keeping the legs warm in the face of cool ambient air, and skirts and trousers aren't exactly the best insulators in the world.

The article doesn't make it clear just how much power this chip can actually generate with a given temperature gradient and surface area, but it begs the question: Could this chip or some variant of it be used to power a prostetic limb, if you were to harness and store the power it generates (say with a supercapacitor), on a 24/7/365 basis? I'm thinking of how a plug-in hybrid car works - charge it while you sleep, use that stored power while you're awake.

Does the average person move around too much during their waking hours to let this work?

Re:Not gonna fly, basic thermodynamics (1)

Ancient_Hacker (751168) | more than 6 years ago | (#22836246)

Okay, let's do the math. The human body dissipates about 150 watts through a surface area of around two square yards. That's about 2600 square inches. Let's say you used a 5x5 inch patch. That's 25 square inches, about 1% of the body surface. So you could at best capture 1% of 150, or 1.5 watts of heat. The heat to electricity efficiency of a typical thermocouple is about 3%. So we might get 45 milliwatts of electricity. Maybe enough to power a watch or calculator or very slow (5 MHz) computer. By comparison a single lithium AA cell can put out 45 milliwatts for about 120 hours.

Wait a minute (1)

Rockin'Robert (997471) | more than 6 years ago | (#22839022)

If the chip is manufactured at, say, room temperature or colder and
produces electric current at 98.6F,
then just make sure you don't get hypothermic - or frigid.
RR
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