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Scientists have found a way to create and cancel magnetic fields at a distance.
The method involves passing electric current through a special arrangement of wires to create a magnetic field it seems to come from another source. This illusion has real applications: imagine an anti-cancer drug that could be delivered directly to a tumor deep in the body through capsules made of magnetic nanoparticles. It is not possible to stick a magnet in the tumor to guide the nanoparticles on their journey, but if you could create a magnetic field from outside the body centered directly on this tumor, you could deliver the drug without invasive procedure.
The strength of a magnetic field decreases with distance from the magnet, and a theorem proven in 1842, Earnshaw’s Theorem, says that it is not possible to create a point of maximum magnetic field strength in empty space.
“If you cannot have a maximum magnetic field in empty space, it means that you cannot create the field of a remote magnetic source without placing a real [magnetic] source at the target location, ”said Rosa Mach-Batlle, a physicist at the Istituto Italiano Di Tecnologia Center for Biomolecular Nanotechnologies in Italy, who led the new research.
Related: 9 interesting facts about magnets
Make the hypothetical real
Mach-Batlle and his colleagues believed they could work around this problem, however. They were inspired by work in optics that uses engineering materials known as metamaterials (designed to have properties not found in any natural material) to bypass resolution limits set by length d wave of light. Likewise, they believed, hypothetical magnetic materials could enable the impossible in the world of magnetic fields.
The researchers envisioned a material with a negative magnetic permeability of 1. The magnetic permeability of a material indicates how much that material increases or decreases a magnetic field when exposed to that field. In a material with a magnetic permeability of minus 1, the direction of the magnetism induced in the material would be the opposite of the direction of the initial magnetic field.
Of course, a new method of inducing magnetic fields based on materials that do not exist would not be particularly useful. But even if this hypothetical negative permeability material does not exist, physicists can create some sort of temporary “material” from the electric current flowing through a specific arrangement of wires. This is because current induces magnetism and vice versa, a consequence of Maxwell’s equations of electromagnetism.
Related: Magnetic fields the size of a black hole could be created on Earth, study finds
“At the end of the day, we’re not using any material, we are using a precise arrangement of currents that can be considered an active metamaterial,” Mach-Batlle told Live Science.
To create the field at a distance, Mach-Batlle and his team created a hollow cylinder made up of about 20 threads surrounding a long inner thread. When current passes through these wires, it creates a magnetic field that looks as if the long inner wire is actually on the outside of the device. It is the electromagnetic equivalent of a ventriloquist who throws his voice; the source of the field is not actually outside the device, but the field itself is indistinguishable from the field that would have resulted if the source was outside the device.
“We create the illusion of having this source at a distance,” Mach-Batlle said. The researchers published their results on October 23 in the journal Physical examination letters
Biomedical applications
There are still questions about the effectiveness of this method for real world applications. A special feature of the system is that there is an area of very strong magnetic fields between the wire cylinder and the remote field. This region could interfere with some research applications, Mach-Batlle said, but whether or not that’s problematic probably depends on what you’re trying to do with the terrain.
Possible applications beyond drug delivery include the cancellation of distant magnetic fields, a technique that could be useful in quantum computing to reduce “noise” from external fields that can interfere with measurements. Another use could be the enhancement of transcranial magnetic stimulation, which uses magnets to stimulate neurons in the brain to be processed. the Depression. Being able to control magnetic fields from a distance could improve the targeting of transcranial magnetic stimulation, so that doctors can better focus on particular regions of the body. human brain.
The researchers then hope to build a configuration of wires that allows the creation of 3D magnetic fields at a distance.
Originally posted on Live Science.
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