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Powering prosthetics with thoughts alone

  • Modern prosthetic devices offer hope of a more active life for amputees
  • Thought-controlled prosthetic arm being trialed in United States in October
  • Lower-limb prosthetics much improved by recent advances in tech and materials

(CNN) -- It may be disembodied now, but this cutting-edge robotic arm will soon spring into action as U.S. researchers begin a landmark experiment which, if successful, will see it controlled by mind power.

Starting next month, researchers at Johns Hopkins University's Applied Physics Laboratory (APL) in Maryland and the University of Pittsburgh will begin testing on spinal cord injury patients whose brains have been implanted with a tiny (2mm by 2mm) electrode array.

"When a neuron fires an electrode will pick it up the signal will travel to a transmitter and it will be transmitted to a computer in the arm which then interprets that signal and converts it into a motion," program manager at the APL, Michael McLoughlin explained.

"It's a really exciting point in the program. We've been working on getting to this point for the past five years," he added.

The Modular Prosthetic Limb (MPL) itself weighs in at around nine pounds -- the same as a natural arm -- and comes close to the dexterity of a natural limb, McLoughlin says, offering 22 degrees of motion, including individual finger movement.

We can't do the Vulcan salute! We can't cup the palm. But other than that we can do pretty much everything
--Michael McLoughlin, John Hopkins University

"We can't do the Vulcan salute! We can't cup the palm. But other than that we can do pretty much everything," he said.

The APL was awarded the contract to develop and test the arm on human subjects in 2010 as part of the $100 million Revolutionizing Prosthetics program run by the U.S. Defense Advanced Research Projects Agency (DARPA).

Touch sensors in the fingers and the palm will also pick up vibrations, temperature and surface textures, McLoughlin says, although tests on these won't start until next year.

The goal is for the system to be wireless with everything contained in the body, much like a pacemaker, he says.

"The results of this program will help upper-limb amputees and spinal cord injury patients, as well as those who have lost the ability to use their natural limbs, to have as normal a life as possible despite severe injuries or degenerative neurological disease," McLoughlin said.

A commerically available thought-controlled device may be some way off, but companies like Scottish-based Touch Bionics are meeting the demand for highly sophisticated upper-limb prosthetics.

Their i-LIMB Pulse is the latest in a range of myoelectric prosthetic devices which "utilize the electrical signal generated by the muscles in the remaining portion of the patient's limb."

All five digits on the bionic hand function like a real human hand, says the company.

Lower-limb amputees are also feeling the effects of improving technology.

Kevin Murray, a prosthetist at the UK's National Center for Prosthetics and Orthotics, says advances in materials and technology have been dramatic since he began his career.

"(When I started) the majority of amputees would have been wearing stump socks or occasionally you might see suction sockets above the knee level ... The standard foot was a simple wooden uniaxial foot," Murray said.

"The range available now is huge by comparison to what was around 20-25 years ago."

Ossur, an Icelandic orthopedics company, which supplies South African athlete Oscar Pistorius with his carbon fiber running blades -- called the Flex Foot Cheetah -- is one of the leading innovators in hi-tech lower-limb devices.

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Bionic prostheses such as its "Rheo Knee" use artificial intelligence which adapts to the wearer's gait speed and their walking environment.

The more recent "Power Knee" is the world's first motorized, artificially intelligent prosthesis, Ossur says, helping wearers up steep slopes and stairs as well as reducing wear and tear on the remaining good leg.

"We've started to raise the bar," said Hilmar Janusson, Ossur's Vice President of Research and Development.

"My vision for the future is that we will see the activity level of the people who use our products multiply three to four times."


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