SoylentNews is people
SoylentNews
from the does-it-also-make-the-room-darker? dept.
Researchers at the University of Michigan ran a light emitting diode (LED) with electrodes reversed in order to cool another device mere nanometers away. The approach could lead to new solid-state cooling technology for future microprocessors, which will have so many transistors packed into a small space that current methods can’t remove heat quickly enough.
This could turn out to be important for future smartphones and other computers. With more computing power in smaller and smaller devices, removing the heat from the microprocessor is beginning to limit how much power can be squeezed into a given space.
https://www.rtoz.org/2019/02/18/running-an-led-in-reverse-could-cool-future-computers/
[How does this compare to a Peltier device?
--Ed.]
(Score: 4, Interesting) by Taibhsear on Tuesday February 19 2019, @08:32PM (23 children)
I'm not an electrical engineer but I thought the whole point of a diode was that it can only run in one direction... What kind of star trek reverse polarity shenanigans is going on here?
(Score: 2, Insightful) by Anonymous Coward on Tuesday February 19 2019, @08:41PM
I was thinking the same thing and the article is absolutely no help here.
If I had to guess, I would say that certain diodes that emit light, emit electricity when bombarded by infrared light, i.e. thermal emissions. If you reverse their polarity then the current generated is pumped back to ground thereby providing a pathway of heat return to the power source.
This is literally, only a guess and I've never heard of a substance that both emits light when powered and emits power when lighted. It would be like plugging your solar cell into a battery and having it glow. I guess it might radiate thermally though, so who knows?
We tend to think of light and heat as different things, but they are the same thing just at different frequencies. I've seen and used sound transducers, but a light transducing substance though, to my knowledge does not exist.
(Score: 0) by Anonymous Coward on Tuesday February 19 2019, @08:43PM (2 children)
You are correct. The LED will be in high resistance mode until a reverse breakdown voltage. Then it conducts.
The LED has a tiny crystal deep inside a heat insulating package. Until I see an article that explains the effect in terms of physics, I will consider this article to be a fake. (The link currently returns 403 Forbidden.)
(Score: 4, Informative) by takyon on Tuesday February 19 2019, @09:17PM
This is the real TFA and associated science article:
https://news.umich.edu/running-an-led-in-reverse-could-cool-future-computers/ [umich.edu]
http://dx.doi.org/10.1038/s41586-019-0918-8 [doi.org] (says DOI not found right now)
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Tuesday February 19 2019, @09:24PM
nonsense.. if you do read the actual article then you'll see that they have found a way of sucking up the infrared-heat-radiating-photons -- taking them (their energy) out of the system via the diode. filed that one under freaking-awesome.
(Score: 2) by krishnoid on Tuesday February 19 2019, @08:48PM (5 children)
Now no longer a light emitter, it's now a light sucking diode, with its concomitant psychedelic effects.
(Score: 2) by PartTimeZombie on Tuesday February 19 2019, @09:07PM (4 children)
It still emits, but it is now emitting dark instead of light.
(Score: 1) by fustakrakich on Tuesday February 19 2019, @09:15PM (3 children)
Does it make the room darker?
La politica e i criminali sono la stessa cosa..
(Score: 2) by DannyB on Tuesday February 19 2019, @09:20PM
Not if the room is already at absolute dark.
I'm now going to run a resistor in reverse polarity to increase current flow in the circuit.
What happens to the temperature if I put the reverse polarity LED in series with the reverse polarity resistor?
The lower I set my standards the more accomplishments I have.
(Score: 2) by PartTimeZombie on Tuesday February 19 2019, @10:08PM (1 child)
Yes, unless the room is at absolute dark, as DannyB has pointed out. (Obviously).
(Score: 1) by fustakrakich on Tuesday February 19 2019, @11:26PM
You gotta have pretty good night vision to go around hooking up LEDs and resisters in the dark, don't you?
La politica e i criminali sono la stessa cosa..
(Score: 4, Informative) by noelhenson on Tuesday February 19 2019, @09:09PM (4 children)
In a reversed polarity circuit, an LED will generate a photo-voltaic current when exposed to light. In older LED displays, unused LED segments were sometimes used as light sensors to control the display brightness. For IR remote controls, I have used the IR LED as the IR sensor as well.
I believe it could be this effect that carries away the heat. I still don't think it could carry away enough heat to make any real difference.
(Score: 2) by Snow on Tuesday February 19 2019, @09:20PM (2 children)
Interesting.
So essentially it's a solar panel, but tuned for infrared (heat)?
The article is scant on details, but I was picturing something similar to the Peltier effect where the heat is moved to another location. In this case, the heat is not moved, but rather converted to electricity?
(Score: 0) by Anonymous Coward on Tuesday February 19 2019, @09:27PM (1 child)
yes. the photon's charge gets carried out as electrons. this freaking awesome insight could just make the way for viable 3D computing structures in which waste heat converts back to charge.
(Score: 2) by qzm on Wednesday February 20 2019, @10:57AM
if only efficiency didnt matter..
(Score: 3, Informative) by jmorris on Wednesday February 20 2019, @03:40AM
Yup, many forget or never realized the truth of diodes.
All PN junctions are diodes.
All PN junctions are zener diodes, although sometimes they are destroyed at about the same reverse voltage. Just depends on the way it was designed.
All PN junctions are LEDs at some wavelength, often infrared.
All PN junctions are photodiodes, sensitive to some wavelengths more than others.
All PN junctions are solar cells, usually very poor ones because so small but still...
The reactions to light are often eliminated by encapsulating them in an opaque substance such as epoxy.
(Score: 4, Funny) by Thexalon on Tuesday February 19 2019, @10:37PM (4 children)
It's been a while since I've played with this stuff, but I recall running LEDs the wrong way on DC circuits at least would tend to turn them into "Smoke Emitting Diodes".
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 0) by Anonymous Coward on Tuesday February 19 2019, @10:52PM
Probably a much lower voltage required, or possibly no voltage since it becomes a source?
(Score: 3, Informative) by Veyrdite on Wednesday February 20 2019, @02:00AM
This will only happen if you're not limiting power to them. Backwards an LED will block until a certain threshold voltage, then it will start conducting, just like any diode.
Source: I regularly run LEDs backwards because I'm lazy in my designs and/or clumsy in my assembly.
(Score: 4, Funny) by hamsterdan on Wednesday February 20 2019, @03:27AM (1 child)
Well, all diodes emit light at least once
(Score: 2) by DannyB on Wednesday February 20 2019, @03:23PM
Also true of Light Emitting Resistors too!
As a teen, in about 1976 ish, I put a red LED across a small rectangular 9V battery for fun. Easy to do. Just bend the LED leads a bit. Hold it with needle nose, and touch it to the battery posts. Boy this is going to be very bright but won't last long.
POOF! It exploded faster than I could have imagined. The first thing I realized was the loud POP. Then I also realized I had heard the cap of the LED hit the ceiling. Then I realized I could smell it. It all happened so fast. Like pulling the trigger on a gun.
The lower I set my standards the more accomplishments I have.
(Score: 2) by c0lo on Tuesday February 19 2019, @10:37PM
Nobody is perfect, see the leakage current of a diode [learningaboutelectronics.com]
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Wednesday February 20 2019, @06:38AM
Spock is now a swash-buckling chick-magnet with a big pointy dick, and Kirk plays 3D chess all day.
(Score: 2) by DannyB on Wednesday February 20 2019, @03:27PM
Data says it is nothing compared to when you subject the reverse polarity LED to an inverse vertiron particle displacement field. Spock adds that it works better with a hiesenberg compensator.
The lower I set my standards the more accomplishments I have.