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Researcher Steven Novack with the U.S. Department of Energy's Idaho National Laboratory showcases the arrays of nanoantennas print on plastic. The material, developed by his team, could yield breakthroughs both in cooling and in solar power collection.  (Source: U.S. Department of Energy's Idaho National Laboratory)

A view of the nanoantennas taken by an electron microscope.  (Source: U.S. Department of Energy's Idaho National Laboratory)

The new material is very flexible and could be printed at a rate of "yards per minute" according to Mr. Novack.  (Source: U.S. Department of Energy's Idaho National Laboratory)
New technology could one day cool PC components and recharge consumer electronics, collecting energy even at night

Imagine your iPod or Blackberry has lost its charge.  Now imagine taking it out of your pocket and laying it on your desk in you cubicle for a few minutes.  After soaking up the light for a few minutes, the phone powers back to life with enough juice to make a call.  No, it wouldn't be by magic, rather this is the scenario envisioned by researchers at the U.S. Department of Energy's Idaho National Laboratory who have developed a unique kind of flexible solar cell.

The new cells consist of massive arrays of nanoantennas, which can collect energy from light and other sources.  The INL team discovered a way to mass produce these arrays on flexible sheets of plastic.  The only crucial problem remaining unresolved is developing additional components to harvest the collected energy by transforming it to electricity.

At the American Society of Mechanical Engineers 2008 2nd International Conference on Energy Sustainability, engineers from the INL presented their findings and revealed their visions of the tech which they hope will one day cover cars and consumer electronics in replenishing skins.  The skins could also act as cooling devices by drawing away waste heat, according to the researchers.

The nanoantennas absorb a targeted wavelength range of mid-infrared rays.  The Earth continuously emits these rays thanks to the solar energy that it absorbs during the day.  This would allow for continuous solar panel operation, in theory.  Traditional panels can only absorb visible light and thus are idle at night.

The INL physicist who led the team, Steven Novack, describes, "Every process in our industrial world creates waste heat.  It's energy that we just throw away."

Mr. Novack worked with INL engineer Dale Kotter, W. Dennis Slafer of MicroContinuum, Inc. and Patrick Pinhero, now at the University of Missouri to design the nanoantennas -- tiny gold squares or spirals set on polyethylene, a plastic commonly found in plastic bags.  The effort marks perhaps the first successful effort to capture infrared rays with nanoantennas.  Past efforts have been able to harvest other lower-frequency wavelengths but have fallen short with high-frequency wavelengths like IR.  This is due in part to the fact that materials' properties change at high frequencies.

Gold was selected after testing it, manganese and copper's reactions to IR rays.  After careful computer design, an antenna which could collect 92 percent of the energy from infrared rays was achieved in theoretical simulations.

Next, the researchers moved to making a prototype, etching silicon wafers with the antenna pattern.  A just slightly less efficient prototype was produced that harvest 80 percent of the energy.  Finally a stamp-and-repeat method was used to emboss thousands of the antennas on thin sheets of plastic.  The plastic skin produced is currently undergoing efficiency testing, but is expected to perform similarly to the first prototype.

As heat typically is emitted as IR rays from many objects, the antennas could cool objects by collecting these rays and reemitting them at a harmless wavelength.  This could be used on a large scale, or on a smaller scale for computer component cooling.

A major obstacle remains in that though the device already produces alternating current, it alternates at a rate of trillions of times per second, far to fast for modern rectifiers to convert to DC current.  Further, the current smallest rectifier would need to be shrunk to a thousandth of its size to fit next to the nanoantenna.  This would require new manufacturing techniques.  An alternative might be to develop nanodevices to slow down the alternating current to more manageable levels.

The light at the end of the tunnel, so to speak, should these problems be overcome, is the production of much cheaper and more efficient solar cells.  Current cells only have an efficiency of around 20 percent, due to the inherent inefficiency of the chemical reactions used to harvest visible light.  More exotic cell materials have promised higher efficiencies, but they remain too expensive and difficult to utilize.

Nanoantennas on the other hand can harvest rays much more efficiently.  Further, they can be formed in multiple layers, with each layer tuned to a different part of the spectrum based on the antenna design.  Mr. Novack imagines manufacturers to eventually be producing "several yards per minute" of the material.

The program is a part of the U.S. Department of Energy's ongoing alternative energy investments

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chop chop
By piroroadkill on 8/11/2008 1:28:31 PM , Rating: 2
They need to hurry this to market in a cheap manner as soon as possible, surely.

RE: chop chop
By FaceMaster on 8/11/2008 1:33:35 PM , Rating: 4
Finally! A decent sunscreen for my car

RE: chop chop
By daftrok on 8/11/2008 9:01:51 PM , Rating: 2
A decent sunscreen for anything, really. You could use this as window shutters or cover your roof with it. Too bad its a glossy finish and not matte.

RE: chop chop
By ViroMan on 8/12/2008 3:46:49 AM , Rating: 2
lol ya.. this would suck to place on your roof in its glossy form. On a sunny day you couldn't step foot out your front door without getting hammered by the sun from your neighbors roof across the street.

RE: chop chop
By paydirt on 8/12/2008 9:35:08 AM , Rating: 2
"Nanu nanu" er... Nano nano

RE: chop chop
By mmcdonalataocdotgov on 8/13/2008 7:53:17 AM , Rating: 2
Yeesh. The technical obstacles are significant and years away from being resolved.

File this one under "What ever happened to..."

By knowom on 8/11/2008 2:27:31 PM , Rating: 3
All these theoretical alternative energy miracle products are great in all, but until one is out on the market to consumers and more importantly a household product hardly anything to be excited over.

RE: umm...neat
By Dark Legion on 8/11/2008 3:13:29 PM , Rating: 2
Especially when they say something as vague as "Mr. Novack imagines manufacturers to eventually be producing "several yards per minute" of the material." Not even some sort of estimate, just "eventually". It would also be nice to see how much this may cost compared to current technology, or an estimate for how much it will cost when/if this is mass-manufactured.

RE: umm...neat
By OxBow on 8/11/2008 5:44:20 PM , Rating: 2
Without some method to actually harness the juice, his "eventually" is pretty optimistic.

It seems like we hear about two or three new breakthroughs every week in terms of green energy, whether solar or wind power, new vehicle tech, biofuels...

What we don't hear about is anybody marrying the technologies together. It might be happening, but it doesn't seem that we hear about it. I'd love to hear about a clearinghouse where these ideas can be put together. Just like Paris Hiltons energy plan, take the good from both ideas and let's move forward.

I can't believe I just quoted Paris Hilton, please forgive me.

RE: umm...neat
By Icelight on 8/12/2008 12:52:32 PM , Rating: 2
This'll be another "...and we'll never hear about it again." sort of thing I bet.

Quantum Efficiency
By Goty on 8/11/2008 2:43:32 PM , Rating: 3
A QE of 92% is great, even if it IS only the theoretical limit. Even if the actual value comes in much lower, it should still be much better than current solar panel technology.

RE: Quantum Efficiency
By sleepeeg3 on 8/11/2008 8:25:16 PM , Rating: 2
..92% of only IR. Whatever that translates into. How much energy is there to capture only from the IR spectrum?

RE: Quantum Efficiency
By masher2 on 8/11/2008 9:12:42 PM , Rating: 1
> "How much energy is there to capture only from the IR spectrum? "

The sun actually emits a large percentage of its energy in the near-infrared. The original press release for these antenna say they capture in the mid-infrared, by which I assume they mean 30K-70K angstroms. The sun emits almost nothing directly in this'd get more energy by the energy reradiated from the ground or other hot materials.

RE: Quantum Efficiency
By Goty on 8/11/2008 10:52:39 PM , Rating: 2
Atmospheric emissions in the mid-IR are also pretty strong.

Wow interesting
By Smartless on 8/11/2008 2:10:57 PM , Rating: 2
It converts waste heat, sun, and other wavelengths? Sounds very promising... Too bad your AC adapter is going to have to be bigger than a car to stop a trillion cycles. haha.

RE: Wow interesting
By Cullinaire on 8/11/2008 5:34:54 PM , Rating: 2
Not if it's made out of Carbon Nanotubes!!!

RE: Wow interesting
By MrPoletski on 8/12/2008 12:20:11 PM , Rating: 2
yeah looks like it's actually an antenna picking up the light waves coz tens of terahertz sounds about right for IR radiation.

ther is no easy way around that, except to produce a super-duper rectifier, will need to be integrated right down to the cell level with this idea, but mixing gold and semiconductors is gonna be hard, especially if you wanna run it at terahertz...

By rtrski on 8/12/2008 9:29:32 AM , Rating: 2
Look, all they did is come up with an antenna that's resonant in the mid-IR, and produce it on a thin film plastic. That's kind of neat, and a nice first step. But otherwise totally meaningless to all the BS speculation presented in the article and the linked pages.

"Could absorb IR and re-emit at lower wavelengths..." Nothing remotely demonstrated about this. An antenna is simply a coupling mechanism between free-space EM and some form of 'guided' EM mode, antennas are PASSIVE. They don't do frequency multiplication or division. They trap a wave out of the air into a circuit, but it's still at the same frequency, and has to then go somewhere. Otherwise, it comes right back out.

Spiral antennas, square slots, split-ring resonators, etc have all been around forever. Simple wavelength scaling lets you "design" them for almost any frequency range you want. But etching techniques and tolerances might mean you can't get the desired linewidth and spacing for a given application. The only 'new' thing here is that they managed to get a small enough pattern placed on a thin, flexible, and inexpensive material. But without something to connect to, reciprocity says if you receive, you radiate as well. All that mid-IR frequency EM "captured" by the antenna has got to go to a load circuit of some kind, or else it's reflecting right back out as soon as it hits a discontinuity (less some dissipative losses).

If they're just 'block stamping' the antenna pattern, it would be interesting to hear how well they aligned the pattern 'blocks' (certainly they're not stamping each individual spiral, but larger groups thereof). Without the ability to line up your circuitry, you can never realize a larger array. Without the right registration tolerances you're also never connecting any sort of circuitry to these antennas to keep whatever EM they received in the first place.

I'm really becoming more and more disillusioned by the "science" reporting here at Dailytech. Michael still has some pride of authorship, but certain other authors are either ignorant or lazy enough to just parrot whatever grandiose claims anyone else posts (nearly word-for-word, no less) without even performing a basic sniff test.

By jido on 8/12/2008 6:59:24 PM , Rating: 2
The manufacturing first is important. It will likely have applications.
From the comments I understand that should not be called a solar cell, except if we solve the issue of the rectifier. It is an antenna (not even tuned to the sun radiations).

BTW how does the rectifier work? Does it dephase the signal to generate a non-alternated mostly-flat output? If so could the same be achieved with several antennas oscillating with a slightly different phase.

By Shadowself on 8/11/2008 1:45:04 PM , Rating: 2
The only crucial problem remaining unresolved is developing additional components to harvest the collected energy by transforming it to electricity.

When they have a prototype that includes this capability this will be an development. Until this I will rank it as barely more real than commercial nuclear fusion.

By Avitar on 8/11/2008 5:48:47 PM , Rating: 2
It has to be as small as your DNA. That has been the holdup ever since this structure became a theoretical possibility. It will not be cheap right away but when it does get cheap, it will be everywhere.

By Comdrpopnfresh on 8/11/2008 6:13:51 PM , Rating: 2
Past efforts have been able to harvest other lower-frequency wavelengths but have fallen short with high-frequency wavelengths like IR

IR is a low-frequency electromagnetic wave. The only other forms of light radiation with lower frequencies are microwave and radio.
IR, however, is of a larger wavelength than visible light: Once again, the only typical radiations with a larger wavelength are microwave and radio emissions.

If the quoted portion was intended to mean that microwave and radio EL radiations has been harvested, then the passage is relatively correct. However, it is rather confusing to mention both the frequency and wavelength with the same adjective- as they are inverse properties. It would be most accurate to refer to IR as a waveform , with the properties of either high wavelength, or low frequency.


Are they kidding?
By 2ndKnight on 8/19/2008 2:26:33 PM , Rating: 2
As described this violates the second law of thermodynamics. Everything above near absolute zero gives off some IR. They claim to someday be able to extract energy from one body and transfer it to another without without performing any work. Maxwell's demons can not function and never will.

Offhand, I would say the hangup is in the hypothetical diodes. If it were possible to make them with a small enough forward voltage why bother with the antennas? The thermal movement of the electrons would drive them through these hypothetical one way valves.

By jlips6 on 8/19/2008 8:13:04 PM , Rating: 2
they mention gold...
they do NOT mention price...
How much gold are we talking here for say... 10 square feet?

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