With this method, it will be possible to charge laptops and cell phones without connecting to electricity.
In the picture: power transmission in the air for a distance of two meters from the copper coil on the left to the right coil, where the electric light is fired with a power of 60 watts. The team members who performed the experiment block the line of sight between the two coils with their bodies. In the front row Peter Fisher (left) and Robert Mutaf, in the second row Martin Suliacic and in the third row Andre Kors (left), John Joannapoulos and Aristidis Karlis
"Imagine a future where the transmission of electric power without cables is possible: cell phones, home robots, MP3 players, laptops and other portable electronic accessories will be able to charge themselves without being connected by cables to electricity, thus freeing us from the last cables we have left - the electric cables. Some of these devices may not even require bulky batteries to operate. This is what Franklin Headley, from the Institute for Military Nanotechnology at MIT, writes in an article that appeared on the Institute's website last week, following a study carried out by a team of researchers from the Department of Physics, the Department of Electrical Experimentation and Computer Science, and the Institute for Military Nanotechnology (ISN - Institute for Soldier Nanotechnologies) in which the researchers were able to experimentally demonstrate a step Important towards achieving this future step.
The researchers - Ander Kors, Aristidis Claris, Robert Mutaf, Prof. Peter Fisher and Prof. John Joanopoulos (Chairman of the ISN) and the head of the team, Prof. Marin Sulaičić managed to realize their theoretical prediction, and turn on a light bulb At a power of 60 watts from a power source that was more than 2 meters away from the bulb without any physical connection between the source and the bulb. The MIT team called this capability WiTricity (short for wireless electricity). The work was published in the June 7 issue of the journal Science Express - the online edition of the journal Science.
Beeps late at night
The story began late at night several years ago, when Suliacic was standing in his pajamas looking at his cell phone in the corner of the kitchen. "This is the sixth time that month that I woke up to the beeping of the cell phone reminding me that I forgot to charge it. I thought to myself that it would be wonderful if I could trust it to recharge itself. To make this possible, a way to transmit the electricity through the air was required, so Suliacic began to think about what physical phenomenon could help make the dream a reality.
Several methods for wireless transmission of electricity have been known for many years. Perhaps the best example is electromagnetic radiation such as radio waves. However, while such radiation is excellent for the wireless transmission of information, it is not available for use in the transmission of electricity. Since the radiation is scattered in all directions, most of the power is wasted into open space. Another way is to use direct electromagnetic radiation such as a laser, but this is impractical and it is also possible that this method is dangerous. It requires an uninterrupted line of sight between the source and the device, as well as a sophisticated tracking system when the device you want to supply electricity to is a mobile device.
The key: integrated magnetic resonance
Instead of these methods, the WiTricity is based on the use of integrated magnetic resonance. Two objects resonating at the same resonant frequency are able to transfer energy efficiently when loosely interacting with another non-resonating object. A child on a swing is an excellent example of this. A swing is a type of mechanical resonance so that only when the child pushes with his legs at the natural frequency of the swing, he can give the swing additional movement energy. Another example is that of acoustic resonance. In a room with 100 identical wine glasses, each filled with wine at a different height, so each has a different resonant frequency. If an opera singer sings a single note loudly enough in the room, the glass of the appropriate frequency may accumulate enough energy to even explode, while no effect will be felt on the other glasses.
"In every system of integrated resonance, there is a region known as the tight operating region. If operation in this area can be ensured in a given system, the energy transfer can be highly efficient.
While these conditions are universal, and suitable for any type of resonance (acoustic, mechanical, electromagnetic), the MIT team focused on one particular type - magnetically coupled resonators. The team studied a system in which two magnetically resonant objects tend to coordinate frequencies in the magnetic field. They were able to detect the tight domain in this system, even when the distance between them was many times greater than the size of the objects. In this way, the researchers were able to transfer energy efficiently.
The method is particularly effective for everyday applications because most materials react only weakly with magnetic fields, so the interference to other objects in the environment is even more suppressed. "The fact that magnetic fields react so weakly with biological creatures is also important from the safety aspect," says Kors, a doctoral student in physics.
The researchers developed a system with two copper coils, with each of the systems operating at its own frequency. One of the coils was connected to a power source and became the sending unit. Instead of radiating into the environment and polluting it with electromagnetic waves, it filled the surrounding air with harmless magnetic radiation in the megahertz frequency range. The non-radiating field was used as a range to transmit the electrical power to the second coil (the receiving unit), which was designed to resonate with the field. The resonant nature of the process ensures a strong connection between the sending device and the receiving device, and a weak connection with the rest around them.
WiTricity relies on well-known laws of physics, so the question arises, why wasn't this thought of earlier? "In the past, there was not such a great demand for these systems, so there was no motivation to investigate in depth" says Joannapoulos who added: "Over the past few years portable electronic devices such as laptops, cell phones, IPODs and even robots used for various jobs in the home and yard such as Vacuum cleaners and lawnmowers have become wireless, requiring batteries that need to be recharged frequently."
And Suliacic adds: "When my son was three years old, we visited his grandparents' house. They had a 20-year-old phone and my son picked up the receiver and asked: "Why is the phone connected to the wall by a wire? - This is the perception of a child who grew up in the wireless world. My response was, 'Is that weird? I hope we can get rid of more cables and also batteries soon."
The work was funded by the Military Research Center (Institute for Soldier Nanotechnologies), the National Science Foundation and the US Department of Energy.
There is wireless communication - now also wireless electricity
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After the above experiment.. let them check carefully if they haven't grown some kind of tail..