Thanks to the Walt Disney
Company, wall plugs might become a thing of the past. Scientists at Disney Research
have found a highly efficient way to deliver power to devices wirelessly across
a room, using magnetic fields.
More than a century
ago the great inventor Nikola Tesla unveiled a plan to provide free electricity
to the world: he proposed setting up a wave of electricity bouncing constantly
between the Earth and the upper atmosphere. All electrical devices would be
tuned to the frequency of this wave and receive energy from it, creating a
wirelessly powered world.
“Well that idea didn’t
really work out,” says
Alanson Sample, who leads the Wireless Systems group at Disney Research, “but
it gave us some inspiration for ways to set up wireless power in large spaces.
“What we really want
is a three dimensional charging experience where you walk in into your living
room or office, and your cell phone is charged simply by walking in.”
One problem with
Tesla’s plan was it used very high voltage electric fields, which are
potentially dangerous. Instead, Sample and his team use oscillating magnetic
fields, which harmlessly pass through human bodes – and anything else.
Devices such as phones
or computers, anywhere in the space, can tap in to wireless power using
internal circuitry that resonates at the same frequency as the magnetic field—a
bit like how a tuning fork can resonate if you hit the right note on a piano.
After working their
idea out on paper, Sample and his team tested it by building a special room and
powering various devices inside. A copper pipe was erected in the middle of it –
a little like a pole-dancing set-up – while the walls, ceiling and floor were
lined with aluminium panels.
Currents ran up and
down the pole 1.3 million times per second, generating an oscillating magnetic
field at that frequency.
The field can deliver
up to 1.9 kilowatts of power inside the room, “which is equivalent to charging
320 USB devices,” the authors write in
PLoS One. In a demonstration,
Sample’s team operated lamps, a fan, a toy car, a phone, a fan and some LEDs
Cleverly, the wireless
system doesn’t generate a strong field unless a device is tapping in to it—so
energy is not wasted when the room is empty. Lights off means power off.
Just don’t bring your
device too close to the pole: that could damage it, or wipe its memory. The
team propose adding a decorative wall or barrier to prevent this.
According to Sample –
who worked previously on wireless systems for cardiac implants – the technology could be scaled scaled down to
make a charging box for a toddler’s toys, or scaled up to the size of a
The current design,
however, results in a significant problem. With the walls, ceiling and floor
all made from aluminium panels, outside signals are blocked. Your phone might
be charging in your pocket, but it won’t receive any calls. As the system
improves, though, there may be scope to reduce the amount of cladding and let
some data through.
Cathal O'Connell is a science writer based in Melbourne.
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