A team of leading scientists from MIT’s Department of Electrical Engineering and Computer Science, Department of Physics, and Institute for Soldier Nanotechnologies have demonstrated a concept they call “WiTricity” (wireless electricity). In the photo to the left, we witness power being transferred across two coils over a distance of 2m, made clear by the presence of the gleaming 60W lightbulb on the right. The transfer of power was successful in spite of the fact that the team obstructed the direct line of site of the two coils. Although electromagnetic radiation is an alternative method of transmitting power wirelessly and has been around for a long time (i.e. radio waves), radiation diffuses in all directions and is thus not concentrated enough to be feasible for power transmission. Lasers would work, but can be dangerous and require direct line of sight between the power source and the device.
"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."
"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."
The team at MIT has compiled a basic design for their self-resonant system, which consists of two copper coils. The power source coil irradiates the environment with a magnetic field that oscillates at a specific frequency, which the receiving coil is attuned to. With laptop-sized coils, there would be more than enough power to run a laptop computer over room-sized distances, regardless of direction and shape of the surrounding space, and regardless of obstacles. WiTricity is certainly not a new concept. We are not talking about a revolutionary breakthrough or a world-changing invention. What we are talking about is a change in demand. With so many portable devices now in popular use –for instance the iPod, cell phones, MP3 players, laptops, mouses, and keyboards - revisiting WiTricity may not be a bad idea.