This is a most excellent place for technology news and articles.
In no way is this a discovery.
This is what crystal diode radios are from the '40s.
Some guy built one in Japan, it's basically just a thousand transceivers in a box hooked up to a USB port harvesting radio/wifi signals.
Here's a guy using them to make light:
It's super cool, but not a discovery.
A friend of mine was working on a car chassis and that thing suddenly started to receive radio. You could faintly hear it coming from the chassis and not from somewhere else. We thought we were going crazy. Touching the chassis made it go away.
When I was a kid, I got a stereo system for my birthday one year alongside two big speakers. The speakers, if they stayed powered while the stereo was off, would receive faint traces of radio signal. So round midnight when the house is quiet I could always hear faint voices, just barely loud enough to hear, but quiet enough to make you wonder if you're really hearing it. Nearly scared the dick off me, I thought my parents gave me a haunted stereo. No, turns out it was just haunted by the ghosts of local AM radio.
Haha, that's so cool.
This would be neat for a bunch of passive IoT buttons. No need for a piezo to generate power, good for a couple presses at a time, just simple stuff like that.
Charge up a capacitor and allow a single button press to send a radio signal. Or maybe have enough power to send a WiFi signal.
You're right, that would be the preferred application atm.
I wonder if it could power a sensor. Something like a soil dampness or thermometer, where you only need a few updates per day. Could be pretty cool for passive monitoring applications.
I remember making a crystal diode radio with my dad as a kid. You can still buy kits for those.
From Radio Shack?!
Definitely not new. This is how RFID tags work. They harvest energy from the transmitter to power the circuitry in the tag to send back a response.
And low-power really means low powered... Like... milliamps. If you fed an RFID chip directly, you'd need to supply about 1 mW depending on the specific chip... 1 milliwatt...
In order to feed that chip with a transmitter you feed up to 2W. So up to 99.95% losses... It's NOT economical for any other device that isn't super low power.
Hell Qi charging is just as bad. Qi2, newest and greatest... Which you basically have the devices touching only get up to 80% at absolute best efficiency numbers. Every mm you add, drops that number significantly.
None of this is going to enable "battery free" for basically anything that any consumer would care to be battery free. And honestly I wish we wouldn't pump the airwaves with all sorts of garbage just because it enabled the most minimal amount of "convenience" for things that never needed to be convenient to begin with.
Not new indeed. Kinda reminds me of old Nextel phones that you would put a little LED on the antenna and it would blink from the EMI when sending and receiving data.
Tap-to-pay on credit card chips, too.
https://en.m.wikipedia.org/wiki/Rectenna
What they've done here is use the very old existing rectenna technology and new types of nanoscale rectenna arrays to capture very low energy radio waves without an external antenna. We're taking -20 dBm or 10 μW.
In the end, I welcome any rectenna advances because if we ever build an efficient optical rectenna it'll blow photovoltaics out of the water by efficiency. Optical rectennas are like fusion power in just how revolutionary they would be to our energy economy.
Dang that's actually a super interesting concept. Thanks for the wikipedia link!
Once its implementation is feasible and it can extract the waste energy efficiently, this innovation will enable new types of devices and uses that will be critical for commercial, scientific, medical and personal.
Sounds like it's still more theoretical than realized, at this point. Still, I can't help thinking this would be really cool for something like a watch or hearing aids.
It's realized, just not scaled.
I was a little careless with how I phrased that. They said in the article they've done it, but it's not "realized" in the sense that it's not to a level of practicality that they'd want it to be. It can currently harvest signals to -20dBm, but they think they can get that to -62dBm for greater efficiency.
The main hurdle, according to them, is there's no schottky diode that fits their needs, and they'll have to engineer a new variant (at the nano scale...?). So, still a theoretical possibility on a more practical level, but this is hopeful news nonetheless.
I agree, it's still very hopeful news that this type of research is being conducted at all, I'm still looking forward to transceivers being built into cell phone batteries and slowly trickle charging constantly.
Still, I can’t help thinking this would be really cool for something like a watch
Watches have been solved. You put a solar panel in the watch face. No need for anything more.
Smart watches use too much energy to do any remote powering with at all, short of qi charging/other near-touching power distribution.
it's called an antenna. That's its job.
Isn't that one of Nikola Tesla's inventions? Free electricity through the air?
Nah, that was just blasting a microwave beam at a collector. It would work and be meh on efficiency, but also bake everything between the two points...neat innovative theory, bad idea. Tesla was a smart dude, but his bad ideas were left ignored for a reason.
That's not right... He was trying to achieve wireless power through Earth resonance. Which AFAIK is pretty much now completely debunked as never going to work ... but it tracks with Tesla's world view.
It's kind of crazy how much you can build without a complete understanding... There's probably stuff we think we understand now that we really don't and other stuff left to discover.
how much you can build without a complete understanding
We've never actually never had one. I'd have to check the timelines but Tesla was almost certainly working on a functional, but inaccurate atomic model (Bohr). Medicine is actually a great example of all this. We are so used to just kind of knowing "there's a bad bug or bad gene that's making me sick". Like you may not know the details, but you've got some loose concept a bunch of cells in your body are pissed off. For the vast, vasssssssst history of medicine, it was all empirical, and the thing is, it kind of worked... sometimes.
My favorite example of "knowing without fully understanding" is Mendel and his peas. If you do a 4x4 punnet square (that gene cross thing), and look at the frequency of co-inheritance, you can track how far genes are from on another (because the further they are, the more likely there will be a swap during the shuffle). Thing is... because DNA is an integer thing (no such thing as 'half a base pair') it works DOWN TO THE SINGLE BASE PAIR. Mendel was accurately counting the number of freaking base pairs separating genes without knowing what a base pair, or indeed even really a molecule, was.
Tesla would have lived to see some absolutely nutty stuff in physics. Boltzman, Einstein with relativity, it must have seemed like pure madness at the time.
So yeah, we discover new and interesting stuff all the time. I personally think that some of the weird quantum stuff is going seem as rote in the future as germs do to us now. As in, the same way any lay-person shoved into a time machine would at least be able to give the basics to a medieval European, someone from the future would be like "well I don't remember much about quantum tunneling, but...".
And that's all before getting into some of the bizarre things going on in math itself. Be careful if you look into that stuff though, it's easy to fall into the "Terrance Howard" style rabbit hole. Suffice to say there is some really interesting and unexpected implications we're discovering, but if you don't have a solid grasp of theory, it is easy to be led astray but sources that want to gloss over details to talk about a conclusion that isn't actually supported. It's like if you tried to explain time dilation to an ancient Greek, and they excitedly hopped on their fastest chariot thinking they could "fast forward" to the future, because time moves "more slowly" for you when you're going faster, right?
This sort of thing is already being done with many commercial devices. See www.powercastco.com for one of the companies.
No radio expert here, but would'nt this at some point interfere with the transmissions if deployed at a large scale?
Tale as old as time. And guess what will happen? Wifi signal strength will go down.
This ain't free at all it's more like stealing electricity with extra steps. Though if it does not degrade wifi or radio signal I'm up for it be used aside from just wasting away.
