If wireless power were possible would you invest in the idea? Students at MIT have tested the impossible thought, and they say it is possible to transfer power ‘wirelessly’. Think of it, no more wires to charge your mp3 players, cellphones, laptops, alarm clocks etc. A team from MIT’s Department of Physics, Department of Electrical Engineering and Computer Science, and Institute for Soldier Nanotechnologies (ISN) has experimentally demonstrated an important step toward accomplishing this vision of the future. While the concept does seem to be futuristic, a scientist from the 1900 had developed and tested this theory. His name.. Nicola Tesla!
Various methods of transmitting power wirelessly have been known for centuries. Perhaps the best known example is electromagnetic radiation, such as radio waves. While such radiation is excellent for wireless transmission of information, it is not feasible to use it for power transmission. Since radiation spreads in all directions, a vast majority of power would end up being wasted into free space. One can envision using directed electromagnetic radiation, such as lasers, but this is not very practical and can even be dangerous. It requires an uninterrupted line of sight between the source and the device, as well as a sophisticated tracking mechanism when the device is mobile.
The key: Magnetically coupled resonance
In contrast, WiTricity is based on using coupled resonant objects. Two resonant objects of the same resonant frequency tend to exchange energy efficiently, while interacting weakly with extraneous off-resonant objects. A child on a swing is a good example of this. A swing is a type of mechanical resonance, so only when the child pumps her legs at the natural frequency of the swing is she able to impart substantial energy. Another example involves acoustic resonances: Imagine a room with 100 identical wine glasses, each filled with wine up to a different level, so they all have different resonant frequencies. If an opera singer sings a sufficiently loud single note inside the room, a glass of the corresponding frequency might accumulate sufficient energy to even explode, while not influencing the other glasses. In any system of coupled resonators there often exists a so-called “strongly coupled” regime of operation. If one ensures to operate in that regime in a given system, the energy transfer can be very efficient.
According to the theory, one coil can recharge any device that is in range, as long as the coils have the same resonant frequency.
While these considerations are universal, applying to all kinds of resonances (e.g., acoustic, mechanical, electromagnetic, etc.), the MIT team focused on one particular type: magnetically coupled resonators.
WiTricity is rooted in such well-known laws of physics that it makes one wonder why no one thought of it before. Will we see the end of dusty knotted wires or better yet AAA batteries? I sure hope so, those suckers are always needed in… beepers?