7 ms·

“Superlens” may solve wireless charging dilemma

54 points by jjude 13y ago

interstitial 13y ago
Seems like we can all just unshield our microwave ovens and fry two birds with one dosage of cancer-inducing electromagnetic waves. Honey, dinner's ready and your phone is charged. Little Alex is vomiting again and his hair is all over my new dress!
- mstromb 13y ago
  You seem to have confused non-ionizing radiation (http://en.wikipedia.org/wiki/Non-ionizing_radiation#Health_risks http://en.wikipedia.org/wiki/Non-ionizing_radiation#Health_r...) (the type mentioned in the article) with ionizing radiation (http://en.wikipedia.org/wiki/Ionising_radiation#Biological_effects http://en.wikipedia.org/wiki/Ionising_radiation#Biological_e...) While some sources call into question the health effects of EM radiation, radios aren't causing vomiting and hair loss unless they're also made of radium.
- david927 13y ago
  That's what jumped out to me as well -- I have a huge concern for the potential ill effects to the human body. Plugging in a device is not a huge hardship and is vastly over-shadowed by the potential health risks.
  - XorNot 13y ago
    It really isn't. For one thing, your body doesn't respond to magnetic fields at all.
- userbinator 13y ago
  It already astounds me greatly how much common people don't know the basics about EM fields when we've essentially been immersing ourselves in them for over 100 years. The main danger is power level causing heating/burns - and a microwave operating at 1000W+ is going to do that far more easily than a router with 1W at most.
option_greek 13y ago
Sounds like a fresnel lens for electromagnetic waves.
namuol 13y ago
The problem is that our devices need frequent charges, not that plugging in is especially inconvenient; this battle will be won on the battery-life front.
- nodata 13y ago
  Have you used a wireless charger? You don't really charge your phone, you just put it on an allocated area of your desk.
  - prof_hobart 13y ago
    That's still something that a) you need to remember to do (my phone currently lives in my pocket at work when not in active use) and to undo - i.e. pick it up again when you wander off b) needs you to be near your desk at some point. I can often be away from any power source for many hours at a time - more than long enough to drain an average smartphone's battery with reasonable use.
    - nodata 13y ago
      True, but it's a lot better than fiddling with a cable when you're trying to concentrate on something else.
      - prof_hobart 13y ago
        True, but it's still a lot worse than having a battery that will comfortably last a day regardless of what usage you throw at it.
- deletes 13y ago
  Imagine a charger that homes in on your mobile devices and charges them to a certain distance, without harming objects in between the source and destination. That way you could have them everywhere and battery would be hardly needed.
  - 13y ago
exo762 13y ago
Dilemma, really? noun noun: dilemma; plural noun: dilemmas 1. a situation in which a difficult choice has to be made between two or more alternatives, esp. equally undesirable ones. #firstworldproblems
- cmdli 13y ago
  Dilemma, noun (3b): a difficult or persistent problem. http://www.merriam-webster.com/dictionary/dilemma http://www.merriam-webster.com/dictionary/dilemma
qq66 13y ago
Seems like the type of problem that will be solved in order to sell products to those too lazy to plug in their phones, but in doing so open up entirely new possibilities in medical devices, remote sensing, and other areas.
nardi 13y ago
Does anyone know what happened to magneto-resonance? That sounded like the way wireless charging was going to go a few years ago.
zymhan 13y ago
I had no idea Dell had a blog with actual writers.
svantana 13y ago
I don't see how transmitting the power 10 inches would make charging any easier. The MIT spin-off WiTricity has been working on a better(?) solution since 2007, they have been consistently overpromising and underdelivering, but recently they showed this nice-looking device: http://gigaom.com/2014/01/09/video-wirelessly-charging-your-iphone-5s-over-a-distance-is-nearly-here/ http://gigaom.com/2014/01/09/video-wirelessly-charging-your-... Personally I believe it would need a few meters' range before it becomes really useful - the point where you rarely need to consciously charge your phone because it is always charging when you're at home.
- rjdagost 13y ago
  I was really interested in Witricity and read a few related papers on their technology. There are a few problems that they are not so keen to publicize: (1) If the receiver loop isn't "inside" the transmitter loop along the normal of the loop area then efficiency falls a bit (2) Efficiency depends a lot on the orientation of the device being charged. If the receiver loop isn't very nearly coplanar with the transmitter loop, efficiency bombs (3) Range is fairly limited (4) When you have multiple devices charging concurrently, efficiency falls for every individual device being charged as magnetic resonance cannot be achieved nearly as well for more complicated multi-body flux loops Witricity has been trying to push electric car charging as for that application these downsides don't matter as much. But even there, you get something like 50% efficiency. Do you want to nearly double your electricity costs just to avoid plugging in a cable? Interesting technology, but it doesn't see like a worthwhile proposition to me. General purpose wireless power transmission is a really difficult problem. I was interested in the ultrasonic acoustic approach that uBeam is pursuing but that has its own slew of problems.
tlarkworthy 13y ago
Does anybody know how people come up with the metamaterial designs? Do they just try lots of aesthetically pleasing symmetries out until they find one that works? Or do they have some forward model to predict the outcome before they build it, but given the often inexplicable results that doesn't seem possible. Where do the ideas come from?
- triplepoint217 13y ago
  Yes, we do have some pretty good theories for designing metamaterials. From what I can remember (and quickly look up on the net), one of the leading theories is called transformation optics, and finding a coordinate transform to a coordinate system where the path you want light to take is a straight line. You can work out what your metamaterial has to look like from that coordinate transform. I probably have some of the details of the technique wrong, I am trying to remember a talk from a year ago. If you want more detail, look at John Pendry's papers (he is probably the leading theorist in metamaterials). http://www3.imperial.ac.uk/people/j.pendry http://www3.imperial.ac.uk/people/j.pendry
  - tlarkworthy 13y ago
    oh hot. Thanks a lot. Sounds like another win for eigenvectors :p
cincinnatus 13y ago
The whole push to wireless charging feels like a bad idea. We already are deeply in need of reductions in total global power use or at least efficiency improvements, and wireless charging wastes a huge amount of power. Unless they can figure out how to bring the efficiency in line with direct contact we're better off with clever direct contact without a plug schemes.
- HillRat 13y ago
  This -- the fact that even highly-optimized inductive charging is about 85% as efficient as direct-contact DC seems to get ignored a lot. Having said that, I actually understand the appeal of charging mats and the like, because they replace a small but persistent friction (find a charger, plug in the charger, plug in the phone, unplug the phone, plug the phone back in...) with a near-frictionless experience, if you don't count the cost. I'd like to see better conductive charging designs, but it looks like inductive has won out.

54 points by jjude 13y ago

Seems like we can all just unshield our microwave ovens and fry two birds with one dosage of cancer-inducing electromagnetic waves. Honey, dinner's ready and your phone is charged. Little Alex is vomiting again and his hair is all over my new dress!

mstromb 13y ago
You seem to have confused non-ionizing radiation (http://en.wikipedia.org/wiki/Non-ionizing_radiation#Health_risks http://en.wikipedia.org/wiki/Non-ionizing_radiation#Health_r...) (the type mentioned in the article) with ionizing radiation (http://en.wikipedia.org/wiki/Ionising_radiation#Biological_effects http://en.wikipedia.org/wiki/Ionising_radiation#Biological_e...) While some sources call into question the health effects of EM radiation, radios aren't causing vomiting and hair loss unless they're also made of radium.
david927 13y ago
That's what jumped out to me as well -- I have a huge concern for the potential ill effects to the human body. Plugging in a device is not a huge hardship and is vastly over-shadowed by the potential health risks.
- XorNot 13y ago
  It really isn't. For one thing, your body doesn't respond to magnetic fields at all.
userbinator 13y ago
It already astounds me greatly how much common people don't know the basics about EM fields when we've essentially been immersing ourselves in them for over 100 years. The main danger is power level causing heating/burns - and a microwave operating at 1000W+ is going to do that far more easily than a router with 1W at most.

option_greek 13y ago

Sounds like a fresnel lens for electromagnetic waves.

namuol 13y ago

The problem is that our devices need frequent charges, not that plugging in is especially inconvenient; this battle will be won on the battery-life front.

nodata 13y ago
Have you used a wireless charger? You don't really charge your phone, you just put it on an allocated area of your desk.
- prof_hobart 13y ago
  That's still something that a) you need to remember to do (my phone currently lives in my pocket at work when not in active use) and to undo - i.e. pick it up again when you wander off b) needs you to be near your desk at some point. I can often be away from any power source for many hours at a time - more than long enough to drain an average smartphone's battery with reasonable use.
  - nodata 13y ago
    True, but it's a lot better than fiddling with a cable when you're trying to concentrate on something else.
    - prof_hobart 13y ago
      True, but it's still a lot worse than having a battery that will comfortably last a day regardless of what usage you throw at it.
deletes 13y ago
Imagine a charger that homes in on your mobile devices and charges them to a certain distance, without harming objects in between the source and destination. That way you could have them everywhere and battery would be hardly needed.
- 13y ago

exo762 13y ago

Dilemma, really? noun noun: dilemma; plural noun: dilemmas 1. a situation in which a difficult choice has to be made between two or more alternatives, esp. equally undesirable ones. #firstworldproblems

cmdli 13y ago
Dilemma, noun (3b): a difficult or persistent problem. http://www.merriam-webster.com/dictionary/dilemma http://www.merriam-webster.com/dictionary/dilemma

qq66 13y ago

Seems like the type of problem that will be solved in order to sell products to those too lazy to plug in their phones, but in doing so open up entirely new possibilities in medical devices, remote sensing, and other areas.

nardi 13y ago

Does anyone know what happened to magneto-resonance? That sounded like the way wireless charging was going to go a few years ago.

zymhan 13y ago

I had no idea Dell had a blog with actual writers.

svantana 13y ago

I don't see how transmitting the power 10 inches would make charging any easier. The MIT spin-off WiTricity has been working on a better(?) solution since 2007, they have been consistently overpromising and underdelivering, but recently they showed this nice-looking device: http://gigaom.com/2014/01/09/video-wirelessly-charging-your-iphone-5s-over-a-distance-is-nearly-here/ http://gigaom.com/2014/01/09/video-wirelessly-charging-your-... Personally I believe it would need a few meters' range before it becomes really useful - the point where you rarely need to consciously charge your phone because it is always charging when you're at home.

rjdagost 13y ago
I was really interested in Witricity and read a few related papers on their technology. There are a few problems that they are not so keen to publicize: (1) If the receiver loop isn't "inside" the transmitter loop along the normal of the loop area then efficiency falls a bit (2) Efficiency depends a lot on the orientation of the device being charged. If the receiver loop isn't very nearly coplanar with the transmitter loop, efficiency bombs (3) Range is fairly limited (4) When you have multiple devices charging concurrently, efficiency falls for every individual device being charged as magnetic resonance cannot be achieved nearly as well for more complicated multi-body flux loops Witricity has been trying to push electric car charging as for that application these downsides don't matter as much. But even there, you get something like 50% efficiency. Do you want to nearly double your electricity costs just to avoid plugging in a cable? Interesting technology, but it doesn't see like a worthwhile proposition to me. General purpose wireless power transmission is a really difficult problem. I was interested in the ultrasonic acoustic approach that uBeam is pursuing but that has its own slew of problems.

tlarkworthy 13y ago

Does anybody know how people come up with the metamaterial designs? Do they just try lots of aesthetically pleasing symmetries out until they find one that works? Or do they have some forward model to predict the outcome before they build it, but given the often inexplicable results that doesn't seem possible. Where do the ideas come from?

triplepoint217 13y ago
Yes, we do have some pretty good theories for designing metamaterials. From what I can remember (and quickly look up on the net), one of the leading theories is called transformation optics, and finding a coordinate transform to a coordinate system where the path you want light to take is a straight line. You can work out what your metamaterial has to look like from that coordinate transform. I probably have some of the details of the technique wrong, I am trying to remember a talk from a year ago. If you want more detail, look at John Pendry's papers (he is probably the leading theorist in metamaterials). http://www3.imperial.ac.uk/people/j.pendry http://www3.imperial.ac.uk/people/j.pendry
- tlarkworthy 13y ago
  oh hot. Thanks a lot. Sounds like another win for eigenvectors :p

cincinnatus 13y ago

The whole push to wireless charging feels like a bad idea. We already are deeply in need of reductions in total global power use or at least efficiency improvements, and wireless charging wastes a huge amount of power. Unless they can figure out how to bring the efficiency in line with direct contact we're better off with clever direct contact without a plug schemes.

HillRat 13y ago
This -- the fact that even highly-optimized inductive charging is about 85% as efficient as direct-contact DC seems to get ignored a lot. Having said that, I actually understand the appeal of charging mats and the like, because they replace a small but persistent friction (find a charger, plug in the charger, plug in the phone, unplug the phone, plug the phone back in...) with a near-frictionless experience, if you don't count the cost. I'd like to see better conductive charging designs, but it looks like inductive has won out.