physics: machines
Custom fit: The
Sabolich Lab (shown
here) developed legconforming sockets
that have made
artificial limbs more
comfortable to wear.
modern materials:
Many of today’s high-tech
prostheses are made of
strong, lightweight carbon
fiber or titanium.
Bionic
body
parts
Artificial parts can help rebuild
people from head to toe
P
BACK ON HIS FEET: Marlon Shirley lost his
left foot at age five and is now the fastest
amputee in the world.
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February 14, 2011
©Simon Bruty/Sports Illustrated/Getty Images; Inset: ©Franck Fife/AFP/Getty Images
realistic look:
Some artificial
limbs look like the
real thing, right
down to fine hairs.
Man and Machine:
A passive prosthesis
is not motorized. The
wearer generates the
energy that powers
the device.
[WEB Extra] Go online for a
slideshow about bionic body parts:
www.scholastic.com /scienceworld
atrick Kane, a 13-year-old from the United
Kingdom, looks just like other kids—
except for his robotic hand. With it, he
can tie his shoes, use a fork, and perform
other tasks he was never able to do
before. “My bionic [hand] is amazing. I can do almost
anything with it,” says Patrick. “I’ll even be able to
drive when I’m old enough.”
It may sound like science fiction, but bionic body
parts like Patrick’s are becoming a reality. The word
bionic is used to describe any artificial mechanism
that functions like a living organism or part of a
living organism. And the use of robotic hands is
only one of the ways scientists are melding man and
machine to repair and replace damaged parts. Find
out how artificial upgrades are changing people’s
bodies and lives—sometimes in superhuman ways.
Lifelike Limb
Patrick is the youngest person ever to get a
bionic hand. And his i-LIMB Hand is one of the most
Science World
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World-record sprinter Marlon
Shirley has run 100 meters in a lightning-fast 10.97 seconds—and he has
only one leg. Shirley, who lost his left
bionic hand
HIGH-TECH TEEN:
Patrick Kane, 13,
shows off how he
types with his jetblack i-LIMB.
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February 14, 2011
1
2
3
How it Works
1. A video
camera embedded in glasses
sends images
to a belt-worn
computer.
2. Images are
turned into a
simplified signal
and transmitted
wirelessly to the
eye implant.
foot at age 5 in an accident, runs with
a carbon-fiber prosthesis (a device
that replaces a missing body part).
The prosthetic foot he uses is called
the Flex-Foot Cheetah.
When the J-shaped Cheetah hits the
ground, it compresses, storing energy
3. A receiver on
the eye sends
the signal to an
electrode array
that stimulates
the retina.
4
4. The optic
nerve carries
the signal from
the retina to the
brain for
interpretation.
that would otherwise be absorbed by
a runner’s knee, hip, and lower back.
As the “J” springs back to its original
shape, it releases some of that stored
energy to propel him or her forward.
In 2007, a double amputee and
Cheetah wearer, South African Oscar
How it Works
Each finger on the i-LIMB can bend, touch, point,
and work together to grip and pick up objects.
Fingertip
sensor
Joint
Motor
Gearbox
Housing
Boy: ©Mark Thiessen/National Geographic Stock; X-Ray: Courtesy Johns Hopkins; diagram: Courtesy of MED-EL
Spring In Your Step
bionic eye
Eye diagram: Illustration by Bryan Christie; KANE: © TELEGRAPH MEDIA GROUP LIMITED 2010/JANE MINGAY; DIAGRAM; Courtesy Touch Bionics (2)
advanced ever made (see Bionic
Hand, below). Its jointed digits bend
similarly to real fingers and are
controlled by Patrick’s muscle movements. It can even lift objects roughly
the weight of a refrigerator!
The i-LIMB slips over a person’s
remaining arm. Inside, small electrode
plates make contact with the skin.
These sensors pick up tiny electrical
signals given off by the person’s arm
muscles when he or she flexes and
relaxes as if to open and close a real
hand. The signals are transmitted to a
small computer, which then tells the
robotic fingers to move.
“Things that we all take for
granted, like typing or using a cell
phone, are made possible by the
i-LIMB,” says Danny Sullivan of
Touch Bionics, the company that
developed the hand.
Pistorius, beat several nonamputees
in a national championship race. After
that, the world governing body for
track and field debated whether technological aids gave athletes with physical disabilities an unfair advantage.
They ultimately allowed Pistorius to
try out for the 2008 Olympics, but he
didn’t make the team. “I’ve been competing against able-bodied athletes for
quite some time, and it’s ridiculous
to think that this foot has aided me,”
says Shirley. “I would be a lot faster if
I had both of my natural legs.”
The Cheetah is a passive prosthesis—it does not have powered parts.
But other artificial feet, like one
being developed at the United States
Military Academy at West Point in
New York, use motors to replicate
the movement of an ankle pushing
off the ground. The mechanical foot
has a spring that acts like a tendon
(tissue that connects muscle to bone)
in the ankle. When a person takes
a step, “usually the energy is just
wasted and put into the ground,” says
Will Guinther, a 22-year-old cadet
working on the foot. “But in this case
it’s recaptured by these springs.”
Regaining hearing
and sight
Hundreds of thousands of people
who were once deaf now can hear
thanks to another bionic device
called a cochlear implant (see Bionic
Ear, above). A microphone placed
under a person’s skin is wired to the
cochlea, a snail-shaped tube in the
inner ear that turns sound waves into
nerve impulses.
The microphone picks up sounds,
then a speech processor filters out
a voice from background noise. The
sounds are converted into electrical
impulses and sent to the auditory
nerve, which carries the signals to a
person’s brain where they are translated into recognizable sounds.
Bionic eyes, meanwhile, restore
vision by working similarly to the
3
How it Works
1. The microphone picks up sound.
2. A speech processor separates
useful sounds from background noise.
2
1
5
3. A transmitter sends signals to a
surgically implanted receiver.
4
4. The implanted receiver converts
signals into electric impulses.
5. Electrodes in the cochlea
stimulate the auditory nerve, which
sends signals to the brain.
bionic ear
HEARING REStorED: Children
as young as six months can
receive cochlear implants.
way cochlear implants restore hearing (see Bionic Eye, p. 10 top).
Retinitis pigmentosa and macular
degeneration are two eye diseases
that destroy the photoreceptors, or
light-sensing cells, in the retina (the
tissue covering the back of the eye).
A microchip implanted into the
retina can help some blind people
detect patterns of light and dark, so
they can see the outlines of objects.
Here’s how it works: A camera
mounted on a pair of glasses captures
an image. The image is transmitted
to the microchip as electrical signals,
which are sent through the optic
nerve to the brain for interpretation.
Scientists are developing contact
lenses with microchips too. These
could allow people with good sight
to zoom in for better views or to see
computer displays before their eyes.
Wired For Touch
With artificial sight and sound well
on their way, scientists are trying to
tackle another sense: touch. Robotic
limbs can’t yet allow people to feel
objects. So scientists are working
on bionic skin with sensors that can
detect pressure and temperature and
relay the data to nerve endings.
Touch Bionics already makes a
non-sensing skin that can fit over the
i-LIMB. It can be made to look like
the real thing, right down to the coloring and hair. Patrick has opted not
to disguise his bionic hand, though.
He thinks its robotic look is cool. 9
—Jennifer Marino Walters
Science World
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