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This page contains all of the posts and discussion on MemeStreams referencing the following web page: Need feedback from nerds.... You can find discussions on MemeStreams as you surf the web, even if you aren't a MemeStreams member, using the Threads Bookmarklet.

Need feedback from nerds...
by Decius at 11:24 pm EDT, Jun 7, 2007

The latest technical advance out of MIT could dramatically change the drudgery of recharging portable devices: An MIT research team has figured out how to wirelessly illuminate an unplugged light bulb from seven feet away.

This must be something other than microwave induction, right? My recollection from school was that this sort of thing has been understood for a long time and the cheif problem is that if you walk into the beam it will burn you. Is this safe?!


 
Wireless Non-Radiative Energy Transfer
by possibly noteworthy at 12:30 am EDT, Jun 8, 2007

Decius wrote:

Need feedback from nerds...

Here are some pointers:

A good place to start is with the MIT press release, which describes the work of Marin Soljačić.

On his web site, he points to a paper describing the theory of Wireless Power Transfer; a simplified explanation is also provided in an accompanying press release.

The MIT team has also conducted successful experiments in wireless power transfer, reported today in Science:

Using self-resonant coils in a strongly coupled regime, we experimentally demonstrate efficient non-radiative power transfer over distances of up to eight times the radius of the coils. We demonstrate the ability to transfer 60W with approximately 40% efficiency over distances in excess of two meters. We present a quantitative model describing the power transfer which matches the experimental results to within 5%. We discuss practical applicability and suggest directions for further studies.

The Science article requires a subscription for full text.

However, the free pre-print is available (this is the theory paper cited above):

Efficient wireless non-radiative mid-range energy transfer

We investigate whether, and to what extent, the physical phenomenon of long-lifetime resonant electromagnetic states with localized slowly-evanescent field patterns can be used to transfer energy efficiently over non-negligible distances, even in the presence of extraneous environmental objects. Via detailed theoretical and numerical analyses of typical real-world model-situations and realistic material parameters, we establish that such a non-radiative scheme could indeed be practical for medium-range wireless energy transfer.

His talk at the 2006 AIP Physics Forum was entitled, "Wireless Non-Radiative Energy Transfer", so presumably the method is not the one that Decius remembers from school lessons.

The figures are freely available as a PDF, including a photo: "Figure 3: 60W light-bulb being lit from 2m away."

There is a WIPO patent on the method:

The electromagnetic energy transfer device includes a first resonator structure receiving energy from an external power supply. The first resonator structure has a first Q-factor. A second resonator structure is positioned distal from the first resonator structure, and supplies useful working power to an external load. The second resonator structure has a second Q-factor. The distance between the two resonators can be larger than the characteristic size of each resonator. Non-radiative energy transfer between the first resonator structure and the second resonator structure is mediated through coupling of their resonant-field evanescent tails.


 
RE: Need feedback from nerds...
by k at 8:34 am EDT, Jun 8, 2007

Decius wrote:

The latest technical advance out of MIT could dramatically change the drudgery of recharging portable devices: An MIT research team has figured out how to wirelessly illuminate an unplugged light bulb from seven feet away.

This must be something other than microwave induction, right? My recollection from school was that this sort of thing has been understood for a long time and the cheif problem is that if you walk into the beam it will burn you. Is this safe?!

I think I heard something about this before... I reckon it's just a fancier version of normal induction via electric field. It's cool that they've managed to tune the fields in such a way that it can work at a distance, normally the induction coil and the induced coil need to be close for there to be any efficiency at all.

The E-fields are probably safe, though you recall wondering about people that lived under power lines ;) I imagine it's fine.

[UPDATE: I was completely wrong, it's not at all inductive coupling... i'm interested in reading more... seems like a very cool tech. -k]


  
RE: Need feedback from nerds...
by Catonic at 8:59 am EDT, Jun 12, 2007

k wrote:

Decius wrote:

The latest technical advance out of MIT could dramatically change the drudgery of recharging portable devices: An MIT research team has figured out how to wirelessly illuminate an unplugged light bulb from seven feet away.

This must be something other than microwave induction, right? My recollection from school was that this sort of thing has been understood for a long time and the cheif problem is that if you walk into the beam it will burn you. Is this safe?!

I think I heard something about this before... I reckon it's just a fancier version of normal induction via electric field. It's cool that they've managed to tune the fields in such a way that it can work at a distance, normally the induction coil and the induced coil need to be close for there to be any efficiency at all.

The E-fields are probably safe, though you recall wondering about people that lived under power lines ;) I imagine it's fine.

[UPDATE: I was completely wrong, it's not at all inductive coupling... i'm interested in reading more... seems like a very cool tech. -k]

I smell something rank... did someone walk through the pasture on the way in?

Ok I finally got a copy of the PDF (9.8Kbit/s, whee!) and got a look at this. Prior Art: 1901 Parlor Tricks, Marconi and Tesla. There is nothing new about this at all. It's not inductive coupling, it's RF. Perhaps a little close, so it may be a not quite formed electromagnetic wave, but it's still pretty damn close in my book.


 
RE: Need feedback from nerds...
by Catonic at 9:01 am EDT, Jun 12, 2007

Decius wrote:
This must be something other than microwave induction, right? My recollection from school was that this sort of thing has been understood for a long time and the cheif problem is that if you walk into the beam it will burn you. Is this safe?!

shhh... if you don't speak so loud the proles won't realize they are being exposed en masse to the sterilization rays....


 
 
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