Microchip Powered by Body Heat

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.

Powered by heat?

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?

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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?

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.

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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

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(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 cons

Re:Powered by heat?

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...

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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 re

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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?

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"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.

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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 usefu

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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.

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As my struggle is usually to burn more calories, this wouldn't be unwelcome.

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Roads? Where we're going, we don't need roads...

Implantable devices running off body heat?

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...

But i am a cold hearted bastard

you insensitive clod!

Dupe!

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

It might work...

"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.

cochlear implants ...

... 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.

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

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

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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...).

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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

Haven't we all seen this movie?

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.

Wow, a dupe of the dupe... Grand-dupe?

This research has been covered at least twice on Slashdot recently:

Researchers Design Microchip Ten Times More Efficient [slashdot.org]

Low Voltage Is Key To Energy-Efficient Chip [slashdot.org]

Maybe those should be included as related articles in the summary, or something...

Not gonna fly, basic thermodynamics

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

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Nah, that would ruin the temperature gradient.