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Scientists Create Super-Thin 'Sheet' That Could Charge Our Phones (theguardian.com)
An anonymous reader quotes a report from The Guardian: Scientists at Massachusetts Institute of Technology (MIT) have created super-thin, bendy materials that absorb wireless internet and other electromagnetic waves in the air and turn them into electricity. The lead researcher, Tomas Palacios, said the breakthrough paved the way for energy-harvesting covers ranging from tablecloths to giant wrappers for buildings that extract energy from the environment to power sensors and other electronics. Details have been published in the journal Nature. Palacios and his colleagues connected a bendy antenna to a flexible semiconductor layer only three atoms thick. The antenna picks up wifi and other radio-frequency signals and turns them into an alternating current. This flows into the molybdenum disulphide semiconductor, where it is converted into a direct electrical current. [M]olybdenum disulphide film can be produced in sheets on industrial roll-to-roll machines, meaning they can be made large enough to capture useful amounts of energy.
Ambient wifi signals can fill an office with more than 100 microwatts of power that is ripe to be scavenged by energy-harvesting devices. The MIT system has an efficiency of between 30% and 40%, producing about 40 microwatts when exposed to signals bearing 150 microwatts of power in laboratory tests. "It doesn't sound like much compared with the 60 watts that a computer needs, but you can still do a lot with it," Palacios said. "You can design a wide range of sensors, for environmental monitoring or chemical and biological sensing, which operate at the single microwatt level. Or you could store the electricity in a battery to use later."
Ambient wifi signals can fill an office with more than 100 microwatts of power that is ripe to be scavenged by energy-harvesting devices. The MIT system has an efficiency of between 30% and 40%, producing about 40 microwatts when exposed to signals bearing 150 microwatts of power in laboratory tests. "It doesn't sound like much compared with the 60 watts that a computer needs, but you can still do a lot with it," Palacios said. "You can design a wide range of sensors, for environmental monitoring or chemical and biological sensing, which operate at the single microwatt level. Or you could store the electricity in a battery to use later."
Hasn't this basically been a thing for a long time? Like those old spy microphones they'd power remotely
Phone reception is already bad in a lot of buildings. Would not wrapping a giant layer of bar-feeding fabric around a building I am in make things even worse?
"There is more worth loving than we have strength to love." - Brian Jay Stanley
We need a cure before it gets out of hand. How much energy does it take to make something practical out of this vs how much you might get over it's lifespan? I wonder if a paper-sized sheet could power a mechanical clock. Hey the clocked stopped, the wifi must be down :D
...bendy antenna to a flexible semiconductor layer only three atoms thick...
I believe this is called a diode and we've been converting signals to electricity with them for a very long time (rectifiers). Seems like what they've done is come up with a way to incorporate them into an antenna that could be manufactured in large flexible sheets suitable for deployment on available flat surfaces. Interesting.
Diode
I am not interested in articles about life extension advancements.
Not with microwatts...
Reading about this elsewhere, I believe that the scientists specifically said that this is far from enough power to operate a cell phone. But without the mention of a cell phone, who would waste time on this 'news'?
Furthermore- if you did wrap one of these around your phone, how would it get the radio signals it needs to function?
...omphaloskepsis often...
Journalists say another.
They said it can power tiny sensors that use microwatts of power.
The headline literally claims a million times that, says it could charge a phone.
yes, conductors turn radio waves into electricity, that's what happens in antenna. very bad to be absorbing large amounts, that means you're blocking them and attenuating them.... bad for everyone's wifi, bluetooth, broadcast radio reception, etc.
this is not 'free energy', it gets popular enough and some broadcasters would start demanding some sort of payment
For 100 microwatts? I pay 10 cents per kwhr. So that comes out to 1 cent for every 100,000 hours = 11 years.
What don't I understand here? How is 40uW out of 150uW 30 to 40% efficiency?
Probably designed with integral rectification, not as the necessary tuned circuit.
How do they know it's wireless internet as opposed to any other traffic running over IP?
People at MIT are really smart so they should know.
You pay for the convenience of not being tethered to a power socket.
Unfortunately 100uW is too small to actually make any appreciable difference to your phone's battery life. I did some experiments years ago and if you have a decent set-top antenna pointed at the transmitter you can run a small LCD clock.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
because harvesting EM radiation for free to power your sensors removes that power from the transmission. This means that the general distance to which the signal usually travels is shortened. The emitter will not be happy to need to increase power output to get his signal along only because there are power harvesters along the line.
Atari rules... ermm... ruled.
These aren't scientists. There are 18 authors and 15 are affiliated with electrical engineering departments, one with chemical engineering, one with chemistry, and one with physics. 16 out of 18 are engineers and the author of the article classifies them all as "scientists. God I get fucking tired of this.
" giant wrappers for buildings that extract energy "
The cellphone and wireless-free building where the 'radiation-sensitive' people can live.
But if they wrap buildings in this stuff they will be effectively creating Faraday Shields that interfere with rf propagation. And they will also be creating massive capacitors if wrapped buildings are across from each other.
E Proelio Veritas.
For 100 microwatts?
You're overlooking the terrible conversion between power sent into the transmitting antenna and the power that's actually coming into the room where you're sitting.
very bad to be absorbing large amounts, that means you're blocking them and attenuating them
It seems like WiFi absorbing clothing would be really popular with people that claimed they could feel WiFi or cell signals passing through their body...
"There is more worth loving than we have strength to love." - Brian Jay Stanley
I call it "a piece of wire"
The average smartphone uses 268 milliwatts at idle, screen off. 40 microwatts is hardly worth it.
~Any apparent grammatical or typographic errors are caused by defects in your display device.
Yes it attenuates the signal. No it's not necessarily bad. The open frequencies were made open specifically because there was high signal attenuation through the air at those frequencies. 2.4 GHz and 5 GHz are absorbed by water molecules (so much at 2.4 GHz that microwave ovens operate at 2.45 GHz). The new 60 GHz band is absorbed by atmospheric oxygen. This makes the frequencies relatively useless for long-distance radio communications, but perfect if you going to have multiple short-range communication hotspots because each hotspot will interfere with neighboring hotspots less. The greater signal attenuation actually becomes an advantage in reducing the noise the devices will see from neighboring hotspots using the same frequency.
The fly in the ointment is that the trend is towards directional radio communications. Things like MIMO direct more radio energy in the direction of the intended recipient of the signal, rather than blasting it at equal strength in 360 degrees. So as this trend progresses, it's going to become harder and harder for a device like this to absorb RF power from the air - it's less likely to intersect with the "meaty part" of a directional radio broadcast.
they already use many times that amount of electricity just to stay connected. And then you must worry about display, running apps, etc. that use several orders that amount.
But for small/embeddable sensors, smart dust, or things like that, for smart homes, cities and clothing, and/or for pervasive surveillance, they might fit.
MIT is notorious for these miracle breakthrough news releases about the same time every year. And the miracles, even many years later, never see the light of day. I should start a website detailing them.
You're not realizing the potential scope of what I'm talking about: you're thinking one person, I'm thinking millions of people, plus someone comes up with stationary installations using this technology for whatever purposes. In other words: what are the effects when you scale this up massively?
40 microwatts doesn't sound like a lot of power. That's barely even enough to be called power imo. Lol!
Clickety Click
In other words: what are the effects when you scale this up massively?
When you scale 100 microwatts up a million-fold you get ... 100 watts. Enough to power a lightbulb.
I said 'millions'. And it's not just about the power. It's about the overall electromagnetic effects hoardes of these might have. Just saying "oh, it'll probably be fine" doesn't cut it. Someone would have to do a study.
Umm maybe this didn't occur to the designers but sure you might be able to sap a little more power to charge the cellphone but I'll bet you'll be losing a lot more from the cellphone desperately trying to find a cell tower to connect to because you've killed it's signal reception.
100uW is more than enough to run a microcontroller. For example, the popular ATTINY85 uses 4uA in power-down mode with the watchdog timer active which can give you a periodic interrupt.
It uses 1mA when active. So at 2.8V that would be 280uW while active. You only need to keep the duty cycle below 20% or so.
You could even power a short wireless transmission every 10 minutes or something.
So for a use case, maybe an RFID with built-in temperature sensor for use in refrigerated supply chain applications. The flexible part means that the micro could be embedded inside and the final package would be a semi-flexible adhesive-backed sticker.
People already use the ATTINY with an inductor to create passive RFID tags. (the inductor connects to the digital inputs, not the power supply pins, and the protection diodes rectify the power from the RFID reader; here you could use both)
Sorry for my mistake, I said "280uW" instead of 280mW" so the duty cycle would be much lower. But you could still power a short wireless transmission every 10 minutes.
You are a factor of 10 out, 1mA at 2.8V is 2800 microwatts. 1% duty cycle might be possible, but 100uW is optimistic and also doesn't account for losses after harvesting because the harvesting circuit won't give you a regulated 2.8V.
It's still possible to use for some applications, but if you have the option then solar is likely to be a better bet.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC