Cloaking magnetic fields: The first 'antimagnet' device developed

Sep 23, 2011
Cloaking magnetic fields: The first 'antimagnet' device developed

Spanish researchers have designed what they believe to be a new type of magnetic cloak, which shields objects from external magnetic fields, while at the same time preventing any magnetic internal fields from leaking outside, making the cloak undetectable.

The development of such a device, described as an 'antimagnet', could offer many beneficial applications, such as protecting a ship's hull from mines designed to detonate when a is detected, or allowing patients with pacemakers or cochlear implants to use medical equipment.

In their study, published today, Friday 23 September, in the Institute of Physics and German Physical Society's , researchers have proved that such a cloak could be built using practical and available materials and technologies, and used to develop an array of applications.

Take, for example, a patient with a pacemaker undergoing an . If an MRI's large magnetic field interacts with the pacemaker, it can cause serious damage to both the device and the patient. The metal in the pacemaker could also interact with and distort the MRI's large magnetic field, affecting the machine's detection capabilities.

The researchers, from Universitat Autònoma de Barcelona, are aware that the technology could also be used by criminals to dodge security systems, for example in airports and shops, but they are confident that the new research could benefit society in a positive way, while the risks could be minimized by informing security officials about potential devices, enabling them to anticipate and neutralize problems.

Lead author, Professor Alvar Sanchez, said, "The ideas of this device and their potential applications are far-reaching; however it is conceivable that they could be used for reducing the magnetic signature of forbidden objects, with the consequent threat to security. For these reasons, this research could be taken into account by security officials in order to design safer detection systems and protocols."

The antimagnet has been designed to consist of several layers. The inner layer would consist of a superconducting material that would function to stop a magnetic field from leaking outside of the cloak, which would be very useful to cloak certain metals.

A downside to using this material, however, is that it would distort an external magnetic field placed over the cloak, making it detectable, so the device would need to be combined with several outer layers of metamaterials, which have varying levels of magnetic field permeability, to correct this distortion and leave the magnetic field undisturbed.

The researchers demonstrated the feasibility of the cloak using computer simulations of a ten-layered cylindrical device cloaking a single small magnet.

Impressively, the researchers also showed that the cloak could take on other shapes and function when the cylinder was not fully enclosed, meaning that applications for pacemakers and are even more feasible, given that they require wires to connect to other parts of the body.

"We indeed believe, and hope, that some laboratories could start constructing an antimagnet soon. Of the two components, superconductors are readily available, for example in cylindrical shape, and the key point would be to make the magnetic layers with the desired properties. This may take a bit of work but in principle the ingredients are there," continued Professor Sanchez.

An Institute of Physics spokesperson said, "The research group have put forward a novel and, most importantly, conceivable plan for a magnetic . The obvious next step will be to translate design into fabrication so some of the wide-ranging applications can be realised."

Explore further: First in-situ images of void collapse in explosives

More information: "Antimagnets: controlling magnetic fields with superconductor–metamaterial hybrids" Sanchez et al 2011 New J. Phys. 13 093034 Paper online:

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4.4 / 5 (13) Sep 23, 2011
A more accurate title for the article would be "Magnetic field cloaking device one step closer to reality." In the article's title, the word "Developed" is past tense and implies a prototype device was built and performed as expected. There was no need to exaggerate the researcher's accomplishment, it is impressive enough on its own.
5 / 5 (2) Sep 23, 2011
"The inner layer would consist of a superconducting material" The wisp of boil-off from the cryo-flask might be a give-away...
Given hypothetical 'ambient'(~300K) superconductors, it would be a different matter !
3.7 / 5 (6) Sep 23, 2011
i dub this magnetic cloak technology , MLOAK. as in,
sir, we cannot fire the magenton torpedos at his ship because he's MLOAKED.
,--impossible scotty, no ship that small can have a mloaking device.
, well if he does sir, we' need to find a way to disable his mloack before firing at him.

3.9 / 5 (43) Sep 23, 2011
Wouldn't this allow for the creation of a perpetual motion machine? I'm sure I'm missing something but when I was younger I drew up a design with a magnet attached to a string that when moving left or right will close a magnetic shield in the direction it is moving. Behind each shield is a stationary magnet that will attract the mobile one. As the mobile magnet approaches one of the stationary magnets, the string gains slack and the magnetic shield falls while the magnetic shield on the other magnet is raised by the pulling of the string. The mobile magnet is then pulled towards the other stationary magnet and the process repeats.

When I thought of this I knew it wouldn't work because there was no such magnetic shielding material. I originally thought mu metal might work but mu metal itself is magnetic and the mobile magnet would just stick to the shield. Anyway if I'm correctly understanding this material's properties, why wouldn't my machine work?
not rated yet Sep 23, 2011
FrankHerbert - because moving the magnetic shield across the field takes energy.
5 / 5 (1) Sep 23, 2011
Also, if you used natural magnets, they would eventually demagnetize. If you used an electromagnet, then you'd be using electricity to power the magnets. In either case the cloak itself would require power.
1 / 5 (2) Sep 24, 2011
Wouldn't this allow for the creation of a perpetual motion machine? I'm sure I'm missing something but when I was younger I drew up a design with a magnet attached to a string that when moving left or right will close a magnetic shield in the direction it is moving.

I have a similar idea, but a little more advanced, yet a little simlper ;) it IS possible to build such a machine, however think of something blocking the magnetic flow in ONE place...this can be any thick piece of non-magnetic material...just something to stop the movement until you pull the trigger, at which point it will run for the lifetime of the permanent magnets....
BUT, I said too you may beat me to it lol
But you better be quick, I plan on building multiple prototypes this year, and I will NOT be selling the idea to a power company....its to help us all, not my wallet....
not rated yet Sep 24, 2011
All we really need is a gravity cloak. bending gravity around an object means it would be free of gravity able to jump right into space!
not rated yet Sep 24, 2011
FrankHerbert - because moving the magnetic shield across the field takes energy.

It doesn't say that in the article, I don't know where you got this notion. It supposedly screens a magnetic field from going outside and from moving inside.
5 / 5 (4) Sep 25, 2011
I think the notion that we should be worried about security threats is a bit premature. By the time this tech is developed enough to a point that would-be evil doers may be trying to smuggle things on planes. Passengers to the US will be quite accustomed to full cavity searches. So as long as researchers put off the development of colon wallet I think we are safe.
5 / 5 (1) Sep 25, 2011
antonima - although it doesn't say that in the article, that's the way it works for shields of electric fields, which are close cousins of magnetic fields, and also the way it works for inserting magnets into magnetic fields and mass into gravitational fields, and even for inserting objects into a stream of flowing water. A force diagram shows that unless the universe has some special exemption in its laws for magnetic shields, that's the way it will work for magnetic shields in magnetic fields, too.
1 / 5 (2) Sep 25, 2011
wow, whos the jackass who gave me a 1 when im trying to help them out...ill make sure you dont get one of the devices (of which ive already proven that it will work btw)...
not rated yet Sep 25, 2011
mu-metal is a material that could already 'block' magnetic fields.

2 / 5 (4) Sep 25, 2011
anything requiring superconductors requires cryogenic cooling, so its not likely to be ready for implants into the human body any time soon. Im sure it could have some engineering potential, but medical applications look oversold.