can sense when the user is ready to walk; it relies
on the wearer to shift the weight in his/her hips
before beginning the next step. The Ekso contains
four motors — two at the knees and two at the
hips — to power the walking motion. The controls
can be set to provide more or less assistance to
the patient, so the user can actually exert force
from the body to move the device. Because of this,
the patient builds muscle and works to alleviate
the physical ailments that can come with life in
wheelchair.
Currently, the device is commercially available
for hospitals; patients can utilize the exoskeleton
under medical supervision during physical therapy
sessions. In 2014, the company plans to release a
personal version meant to be worn by a patient on
a regular basis.
In the past, prosthetic limbs were primarily
worn for aesthetic purposes, not functionality.
For thousands of years, prosthetics were made of
wood or metal, and attached to the body with
leather straps; the earliest example of this is a
3,000 year old wooden toe discovered in Egypt.
Knights in the Middle Ages wore artificial limbs
made of iron. Heavy and not very functional, these
were worn to conceal the fact they were missing
limbs, which was considered an embarrassment at
the time.
In the 1500s, French surgeon Ambroise Paré
invented a prosthetic leg that featured a locking
knee as well as a hinged mechanical hand, kicking
off the trend of improvements over the traditional
prosthetic devices.
As medicine and technology has improved,
so have prosthetic limbs, with technological
innovations such as the development of plastic
impacting the design of the devices. As medical
knowledge improved, more patients ended up
surviving amputation surgeries, increasing the
demand for more functional prosthetics.
It is no surprise then, that robotics is also
revolutionizing this area of rehabilitation. Scientists
now have the ability to use signals from the brain
to control prosthetic limbs. In some instances, this
is done through electrodes placed on the skin to
sense electrical signals in the remaining nerves. In
other cases, the remaining nerves are directed to
control an unaffected muscle through a surgical
procedure.
For example, the nerves that once controlled a
patient’s arm would now control part of a muscle
in the chest. The patient can then learn to contract
these muscles in order to signal the robotic
prosthetic to move. Currently, bebionic and i-limb
are advanced hand prosthetic options for
amputees. These products allow individualized
movement of each finger, allowing patients to type
and eat with the hand.
The i-limb also features a grip control system
that locks the fingers into position when gripping
an object after detecting that the proper amount
of pressure has been applied. This allows the user
to confidently grasp an item — like a soda can —
without worrying that the hand will apply too
much pressure and crush it.
The next step for robotic prosthetics is likely
the incorporation of a brain-computer interface. A
brain-computer interface is a system that measures
electrical impulses in the brain and then feeds this
information to a computer where it can be used in
a multitude of ways. Scientists are using these
interfaces to create prosthetics that are even more
realistic than their already impressive predecessors.
By directly implanting electrodes onto the
brain, scientists at the University of Pittsburgh and
Brown University have successfully allowed subjects
to use thought to control a mechanical arm. Earlier
this year, researchers at the Rehabilitation Institute
of Chicago announced that they were testing a
The metal limbs worn by knights in the Middle Ages were
most likely built by the same metalworker who constructed
their armor. These prosthetics were primarily worn to
conceal the missing limb.
Photo courtesy of the BBC.
44 SERVO 12.2013
This 3,000 year old prosthetic toe is the oldest example
of a prosthetic. It was found attached to a mummy
who may have lost the toe as a result of complications
from diabetes. Photo courtesy of the BBC.
