The team consists of (top to bottom, left to right) Andre Kurs, Prof. John Joannopoulos, Aristeidis Karalis, Prof. Marin Soljacic, Prof. Peter Fisher, and Robert Moffatt. (Source: MIT, Aristeidis Karalis)
A 60-watt bulb illuminates for the future of wireless power
"Wireless" isn't exactly a
new concept to computing. Network connectivity, USB devices and even displays
had their cords cut in recent years. Researchers from the Massachusetts
Institute of Technology took the final steps towards cutting the last tether of
the laptop user: the power cord.
Transmitting power wirelessly is traditionally limited to line-of-sight methods
such as microwave or laser, which have a "significant negative
effect" on anyone or anything unfortunate enough to be caught in the
middle.
Playfully dubbed
"WiTricity" by the team, the researchers were able to power a
sixty-watt lightbulb from seven feet away using the principle of magnetically coupled resonance. The basic concept
is similar to existing electromagnetic inductive chargers, but does not suffer
the massive drop in efficiency when distance is increased.
The experiment works as follows. Two magnetic coils resonate at the same
frequency. When one of these coils is attached to a power source, the
resonant magnetic field produced by the coil increases dramatically. The
second, unpowered coil "couples" with the resonating magnetic
field. The resonance from the second coil is then converted back to electricity
for the device.
The MIT researches are quick to tout magnetically coupled resonance over
electromagnetic induction. Aristeidis Karalis, an MIT graduate student
that worked on the project, states, "Here is where the magic of the
resonant coupling comes about. The usual non-resonant magnetic induction would
be almost 1 million times less efficient in this particular system."
In addition to increased efficiency, the WiTricity project does not transmit
biologically harmful electromagnetic radiation during operation. Additionally,
line-of-sight issues present in microwave technology disappear with WiTricity;
magnetic fields are more-or-less unaffected by non-metallic materials in most
environments.
The most current WiTricity
experiments use coils approximately 20" in diameter and operate at
distances of approximately two meters. The team hopes to eventually power
a notebook from a several meters away.
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