DailyTech - Ambient Energy from the Air Captured to Power Wireless Sensors, Microprocessors

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Science Ambient Energy from the Air Captured to Power Wireless Sensors, Microprocessors
Tiffany Kaiser - July 8, 2011 5:45 PM

56 comment(s) - last by damage75.. on Jul 12 at 6:01 AM

Rushi Vyas (Front) with a prototype energy scavenging device, and Manos Tentzeris (Back) holds a flexible antenna inkjet-printed on paper (Source: Georgia Tech Photo: Gary Meek)

Paper-thin polymers are used with inkjet printers to create antennas and sensors, which create scavenging devices that draw energy transmitted by cell phone networks, satellite communications systems and television transmitters

Manos Tentzeris, study leader and a professor in the Georgia Tech School of Electrical and Computer Engineering, along with Rushi Vyas, a graduate student, and a team from Georgia Tech, have managed to capture the energy transmitted by cell phone networks, etc. through the use of scavenging devices, which then use the energy to power networks of wireless sensors, communications chips and microprocessors.

Satellite communications systems, television transmitters and cell phone networks all transmit energy at different bands, which are frequency ranges. The scavenging device captures this energy and converts it from AC to DC, and stores it in capacitors and batteries.

Scientists have found that electromagnetic bands increase dependability of scavenging devices, and acts as a system backup allowing the scavenging device to transmit a wireless distress signal while maintaining "critical functionalities" if a battery package were to fail.

Currently, this technology can "take advantage" of frequencies from FM radio to radar, spanning 100 megahertz (MHz) to over 15 gigahertz (GHz). The use of television bands have led to hundreds of microwatts of power, while multi-band systems are to generate one milliwatt or more.

A standard inkjet printer is used to create the antennas and sensors, along with a "unique in hour recipe" that consists of silver nanoparticles and other nanoparticles. This recipe allows the scientists to print RF components and circuits as well as sensing devices based on carbon nanotubes and other nanomaterials.

"We can now print circuits that are capable of functioning up to 15 GHz -- 60 GHz if we print on a polymer," said Vyas. "So we have seen a frequency operation improvement of two orders of magnitude."

These sensors have already proved to be successful using electromagnetic energy captured from a television station at a half a kilometer away, which powered a temperature sensor.

These self-powered, wireless, paper-based sensors could be used for airport security to detect potential threats, food material storage to identify chemicals that indicate the food has spoiled, bio-monitoring devices in the medical field and as energy savers that monitor temperature and humidity to help save money on air conditioning and heating costs. In addition, the low cost design of thin polymers and inkjet printing make these sensors available for widespread use.

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In other words

By ViroMan on 7/8/2011 6:55:36 PM , Rating: 4

...your cell phone and other wireless transmission ranges will go down the more of these devices there are as it literally sucks the energy out of the air.

RE: In other words

By Odysseus145 on 7/8/2011 9:15:54 PM , Rating: 2

Not unless it's sitting right next to your antenna. Even then not much...

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RE: In other words

By someguy123 on 7/8/2011 9:44:47 PM , Rating: 3

Not much can become massive interference if they were to have these things mass produced.

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RE: In other words

By Odysseus145 on 7/9/2011 6:31:22 PM , Rating: 3

Maybe if you were listening to the radio in a building covered in these things, but otherwise I can't see how that would be so.

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RE: In other words

By Marfoo on 7/8/2011 10:07:35 PM , Rating: 5

It's not going to interfere with your devices, it would have to be directly blocking your signal just like any other physical object. Receiving a signal is much like being able to see the moon at night, just because other people are looking at it doesn't mean it's harder for you to see it.

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RE: In other words

By someguy123 on 7/8/2011 11:09:51 PM , Rating: 1

Your eyes aren't literally sucking up the light reflecting off the moon.

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RE: In other words

By InsGadget on 7/9/2011 2:51:31 PM , Rating: 5

Actually, yes, your eyes are literally sucking the light reflecting off the moon.

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RE: In other words

By someguy123 on 7/9/2011 4:11:30 PM , Rating: 1

I couldn't think if any way of expressing it completely, but you get what I meant. Your eyes aren't taking away light from the source and stopping it from being distributed elsewhere.

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RE: In other words

By invidious on 7/9/2011 9:15:09 PM , Rating: 5

You cant think of the way to express it because you don't understand it. Electromagnet waves are absorbed, reflected, and transferred when they pass from one medium to another. The amount of each is determined by the type of material and thickness of the material.

If one of these devices is directly between your phone and the signal source then yes it will detract slightly from your signal strength. But if it is ANYWHERE else it will have no affect on your signal strength. When a signal is generated the amount of power required is driven by how far you want it to be readable, not how many devices you want to be able to receive it.

And yes, the moon analogy was fairly accurate. The brightness of the moon is not lessened by others looking at it unless they are standing between you and the moon. The only difference is that their body will absorb or reflect all of the light rays while this device will allow much of the radio wave to transfer past it due to the thinness of antenna with respect to the wavelength of the signal.

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RE: In other words

By Odysseus145 on 7/9/2011 6:29:44 PM , Rating: 2

"Sucking" implies that it is actively drawing energy inward like a black hole or something. Your retinas are merely converting whatever light rays that happen to fall on them into electrical signals. It's the same with these energy harvesters. What little energy they are absorbing would (with near certainty) have just faded into the background.

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RE: In other words

By Mitch101 on 7/9/2011 6:48:31 PM , Rating: 3

I worked at places where the people there sucked the life out of the surrounding. If you worked there you would get that black hole feeling.

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RE: In other words

By Bad-Karma on 7/11/2011 4:11:32 AM , Rating: 3

"sucking" isn't the right word. Your eyes are "absorbing" the light reflecting off of the moon.

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RE: In other words

By Autisticgramma on 7/11/2011 6:32:38 PM , Rating: 2

Yes, but it doesn't stop other people from seeing it, unless their eyes are directly behind your head.

Nothing in nature sucks. :)

Your eyes simply measure the light hitting them (within the spectrum they can), regardless of source.

This is the future of powered devices, why make batteries when there is constant flux of energy all around you. Batteries will eventually be for vehicles. Just about everything that uses batteries could probably use this tech.

But good luck deploying it, you cant meter wireless power, I see capitalists balking at the idea. See :
http://en.wikipedia.org/wiki/Wardenclyffe_Tower
http://en.wikipedia.org/wiki/Nikola_Tesla

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RE: In other words

By Solandri on 7/8/11, Rating: -1

RE: In other words

By Marfoo on 7/9/2011 12:21:13 AM , Rating: 2

You aren't "sucking" up that signal, you're just adding more surfaces that block it. My point was that these devices wouldn't degrade your signal by just being around you, they would have to be directly between your antenna and the transmitter in order to degrade you signal, much like a cloud would have to come between your eye and the moon for you too get a degraded view.

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RE: In other words

By someguy123 on 7/9/2011 4:08:44 AM , Rating: 2

Your analogy was that the moon is still visible even though multiple people can see it.

This won't be of concern to things of limited range like home wireless routers, but this would cause interference with things like cell phone reception. Your cell phone won't be getting a good signal if you have many of these devices absorbing your local cell tower's transmissions.

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RE: In other words

By InsGadget on 7/9/2011 3:02:59 PM , Rating: 2

It would probably take millions of things in huge clusters to have the kind of effect you are worrying about.

People don't understand EMI. This is the same problem with people freaking out about cell phones on aircraft. There is basically as much of a chance of your cell phone interfering with your car as it will interfere with an aircraft in flight.

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RE: In other words

By someguy123 on 7/9/2011 4:15:58 PM , Rating: 2

This is different from interference with electrical equipment. Radio transmissions are distributed into the air. There needs to be enough signal for our phones to receive information. These devices aren't introducing interference, they're absorbing the energy. The energy absorption per device may be low but it's not like legal transmission levels are high to begin with.

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RE: In other words

By delphinus100 on 7/9/2011 10:48:56 PM , Rating: 2

(Sigh.) This is no different than if it were another device capturing the same part of the energy purely to get the information it carries...the only difference is that it presumably rectifies it into DC, rather than demodulating the intelligence on it.

And as it's not a matter of recovering the intelligence, it presumably would do so with any radio frequency energy it effectively absorbs. Not just the frequencies cell phones actually transmit/receives on, but antenna resonance being what it is, that's the frequency range where it will most effectively capture the RF that it happens to intercept. Higher or lower, not so much...

The vast majority of the energy in all RF transmissions are absorbed by the environment, or may make it into space, not by the devices designed to receive it. If you're walking as you make a call, the radio frequency energy is still passing through the place you were at a block earlier. If someone else is now in that spot and receiving some of that signal purely to turn it into power, has no effect on you, at all.

A better analogy might be using a photovoltaic panel to turn sunlight into DC power. The Sun shines on all of one side of Earth, regardless. That someone else on the daytime side of the planet is dong the same, doesn't affect you, unless they place their collector where it casts a shadow on yours...

Has the number of broadcast radio or TV receivers tuned to the same station at the same time, ever mattered to the reception of any one of them? Same deal.

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RE: In other words

By Solandri on 7/9/2011 3:59:12 PM , Rating: 3

quote:
You aren't "sucking" up that signal, you're just adding more surfaces that block it.

They block it by sucking it up, as opposed to bending it (prism) or reflecting it away (mirror). Put another way, these things absorb energy from stray EM radiation. They cannot absorb the energy without altering the signal, since that would create a perpetual motion machine. They only way they can harvest energy is by sucking up the energy in EM which passes through them.

quote:
My point was that these devices wouldn't degrade your signal by just being around you, they would have to be directly between your antenna and the transmitter in order to degrade you signal,

I agree. What I said does not contradict that. Just your misinterpretation of it does. Nothing I said implies that these devices could intercept signals which weren't passing through them, which would be rather nonsensical. I'm not sure how you could interpret what I wrote that way considering I used the terms "directly blocked" and "travel right through". Heck, I didn't even know people could be thinking these things could be absorbing signal which wasn't in line of sight until you brought it up.

quote:
much like a cloud would have to come between your eye and the moon for you too get a degraded view.

And like I said, this is a flawed analogy because it implies that obstructions on the ground don't matter. That's simply not the case with radio/TV transmissions. There are lots of obstructions, just that the wavelengths are long enough to pass through them (with some minor distortion in the form of refraction and reflection). But if we pepper the landscape with these devices which suck up this EM waves as they pass through, then your average signal range is going to be degraded.

For example, the lowest bar on the iPhone 4 represents -113 dBm. If I did my math right, thats one 200,000,000,000,000th of a Watt. It wouldn't take much to munge up that signal and turn that "barely getting reception" case into "no signal".

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RE: In other words

By Marfoo on 7/9/2011 4:54:03 PM , Rating: 2

quote:
They block it by sucking it up, as opposed to bending it (prism) or reflecting it away (mirror). Put another way, these things absorb energy from stray EM radiation. They cannot absorb the energy without altering the signal, since that would create a perpetual motion machine. They only way they can harvest energy is by sucking up the energy in EM which passes through them.

No argument here, just to me the word "sucking" would infer that these devices absorb power from signal around them, not just the signal passing through them. The term I used "block" was a generalization of what you just said.

quote:
I agree. What I said does not contradict that. Just your misinterpretation of it does. Nothing I said implies that these devices could intercept signals which weren't passing through them, which would be rather nonsensical. I'm not sure how you could interpret what I wrote that way considering I used the terms "directly blocked" and "travel right through". Heck, I didn't even know people could be thinking these things could be absorbing signal which wasn't in line of sight until you brought it up.

Sorry, lack of antecedant on my part, I didn't specify who I was aiming that towards, it was not you. There was another commenter who seemed to be thinking along these terms, again why I felt sucking was an inaccurate verb.

quote:
And like I said, this is a flawed analogy because it implies that obstructions on the ground don't matter. That's simply not the case with radio/TV transmissions. There are lots of obstructions, just that the wavelengths are long enough to pass through them (with some minor distortion in the form of refraction and reflection). But if we pepper the landscape with these devices which suck up this EM waves as they pass through, then your average signal range is going to be degraded.

I was just trying to present a line of sight analogy, although this one works better for satellite transmissions than it does ground based transmission. And yes I am completely aware line of sight is dependant on the wavelength in question. The problem with these is ideally they would capture power on all wavelengths, and yes in a very cluttered environment such as downtown in a big city they could affect your signal.

Again my main point being, they would have to be directly in between your antenna and the transmitter, not just simply capturing power from the network. (which isn't directed toward you, just other commenters who seem to be confused.)

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RE: In other words

By geekman1024 on 7/9/2011 12:58:35 AM , Rating: 2

A device will block other devices behind it in the line of sight, just like you will block others directly behind you from seeing the moon.

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RE: In other words

By Marfoo on 7/9/2011 1:13:55 AM , Rating: 2

Yeah, exactly what I'm saying. The first guy made it sound like just because these devices are capturing power from the towers means they are degrading your signal, which isn't true unless they are physically in the way.

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RE: In other words

By InsGadget on 7/9/2011 3:06:26 PM , Rating: 2

If, by some infinitesimally small chance one of these DOES block your signal, you could just move a few millimeters to the side and you'd be fine again.

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RE: In other words

By jordanclock on 7/9/2011 12:14:32 AM , Rating: 2

Or you could stick it in floors and baseboards, where a signal would likely just end up going into the ground...

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RE: In other words

By Final8ty on 7/9/2011 5:56:14 AM , Rating: 2

Radio/signals waves do not degrade with the mount of people receiving it.

The suns energy will not degrade with the amount of solar panels that are put up.

Do not confuse internet transmission which work differently to which has an impact with the more people receiving.

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RE: In other words

By seamonkey79 on 7/9/2011 10:22:47 AM , Rating: 2

There's no such thing as a zero-loss energy conversion... That means that in order for energy to be produced by these signals, the signal has to lose energy. It may not be much, individually, but toss enough of these things that pull energy from signals, and they will probably have a detrimental effect on cell phone signal quality, even if they're not in direct line of sight, merely close enough to pull.

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RE: In other words

By Final8ty on 7/9/2011 11:03:25 AM , Rating: 2

Energy transmission & energy conversion are 2 different things.

Antenna transmits energy & to keep it simple just like the sun, how it is received & converted & by how many has no bearing on the source.

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RE: In other words

By Final8ty on 7/9/2011 11:21:27 AM , Rating: 2

Part 2

The transmitter has a max signal/energy strength & its down to the quality of the receiving device on how much of it can pick up.

A device that can pick up 100% signal/energy strength which would not mean less for everyone else.
All devices could pick up 100% signal/energy strength & it would make no difference.

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RE: In other words

By Marfoo on 7/9/2011 5:01:36 PM , Rating: 2

This is correct.

The receive power is directly proportional to the electromagnetic flux through the receive antenna. The solar panel analogy is perfect for this, the solar panel only captures energy that is already coming to it, it will not "suck up energy" and reduce the power density. It will however degrade signal if it's between you and the source (sun), which in this case the analogy is shade.

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RE: In other words

By Final8ty on 7/9/2011 5:24:52 PM , Rating: 2

Indeed.

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RE: In other words

By Odysseus145 on 7/9/2011 6:41:26 PM , Rating: 3

You would be correct if: a) the energy were being removed before the signal hit the transmit antenna or b) 100% of the energy radiated by the transmit antenna was being recovered at receive antennas. (a) is obviously not the case. As for (b), that is wrong as well. In fact, the vast, vast majority of the energy radiated by transmission antennas is lost. That is why there is so much interest in these energy harvesters. They're collecting and using energy that would otherwise be lost.

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RE: In other words

By Fritzr on 7/11/2011 10:49:15 PM , Rating: 2

B occurs in the rare case of the transmitter being inside a Faraday cage. For example a radio bug in a shield room :P

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Taking power from an Alternate Dimension

By JonB on 7/11/2011 11:36:19 AM , Rating: 3

I know this article is about our own "wasted" RF energy being harvested, but does anyone remember the very old SciFi short story about how an inventor came up with an Antenna that could pull in significant power from "somewhere" (as in, he didn't know where, it was just available). All our cars and houses soon became powered this way. Free energy.

Years later, we are visited by people from an Alternate Earth dimension. They are slowly dying because our antennas are literally sucking the energy from their reality.

RE: Taking power from an Alternate Dimension

By damage75 on 7/12/2011 6:01:20 AM , Rating: 2

"Waldo" by Robert A. Heinlein

Every time I see a sign for deKalb corn I think of the antenna receptors from the book :-)

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Why?

By Odysseus145 on 7/8/2011 9:20:41 PM , Rating: 2

I'll admit the research is interesting, but there is very little value to this I can see. RCA came out with a similar product a while back, and it was mathematically proven it would take years just to charge a cell phone. There just isn't that much RF energy to be harvested.

RE: Why?

By Odysseus145 on 7/8/2011 9:34:00 PM , Rating: 2

Ok, it looks like the 1 mW they're producing is good enough for small, very low power sensors like those for temperature. They're shooting for 50 mW though, but it doesn't look like that would be continuous.

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Any way,,,,

By geekman1024 on 7/9/2011 1:01:20 AM , Rating: 3

I think this technology will be a better choice to replace the tin foil hats. Just stick a few of these on your head...

radio generator

By wordsworm on 7/10/2011 4:47:41 AM , Rating: 2

Any chance that energy from the galaxy could be used in a similar way to generate electricity?

Actually...

By Mathos on 7/10/2011 1:44:53 PM , Rating: 2

Actually from what I can see, these thin film devices wouldn't be absorbing the energy in the way you think. What they're actually doing is receiving the wave form of the signal, and using that waveform to generate DC current and voltage on a very low level. All antenna's and signal receivers work the same way. Otherwise if you were in an area full of people on their cell phones, noone would be able to use them because there would be too much power drain from all the localized use of the signal.

It generates electricity the same way as running a magnet between a coil of wires otherwise.

These devices will not "suck up" energy

By damage75 on 7/10/2011 10:38:15 PM , Rating: 2

The worry that these devices could "suck up" RF energy is patently absurd. Think of a chain link fence - here is a little sarcasm - it's amazing anyone can receive TV with those giant fence antennas sucking up the energy! Yes, it's frequency dependent but it makes so little difference it means nothing.

There are antennas that can "suck up" energy - they can double their apparent size by a trick of resonance. They can only be used at a single frequency and are not what is being described here. Even if someone put their device *against* your phone it would have virtually zero affect on the received RF energy.

Further, line-of-sight arguments are also specious. There is so much multi-path diffraction on the cell phone band you could be listening to a signal bounced off your toaster and you'd never know it.

I do apologize for the intensity of this comment, my Air Jordans are too tight.

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By tangtangtan on 7/11/11, Rating: 0

>.<

By Motoman on 7/8/11, Rating: -1

RE: >.<

By SSDMaster on 7/8/2011 6:20:16 PM , Rating: 2

Wow. Bet the ladies love you.

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RE: >.<

By ClownPuncher on 7/8/2011 6:45:22 PM , Rating: 2

Ladies do love grammar. They also love a man with a good education, appreciation for fine at, good metabolism, and an unhealthy obsession with Chewbacca.

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RE: >.<

By Krotchrot on 7/8/2011 8:19:19 PM , Rating: 3

Unfortunately for you, they also like men that can spell.

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RE: >.<

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In my experience, ladies aren't attracted to dimwits. Bad grammar makes you look like a dimwit.

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RE: >.<

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yah, grammer ain't so bad!!

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RE: >.<

By Alexvrb on 7/8/2011 11:30:33 PM , Rating: 4

If the dimwit is also a smooth talker and a bad boy, I don't think they will care that his grammar isn't so hot. Also, what women say that want doesn't always jive with what they're actually attracted to.

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RE: >.<

By StevoLincolnite on 7/9/2011 11:02:20 AM , Rating: 2

quote:
In my experience, ladies aren't attracted to dimwits. Bad grammar makes you look like a dimwit.

Soooooo wrong.

Everyone has different tastes.
One Woman may like a well educated nicely dressed clean guy.
The next Woman may like a bad boy mechanic who couldn't spell.

You could also have a Woman that likes their men muscled and toned, another likes a bit of baby fat on 'em.

Hopefully you realize one day that you cannot predict what anyone wants with 100% accuracy.

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By babanbang on 7/8/11, Rating: -1

RE: gdaga

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