Another Breakthrough in Modern Science
About 9 years ago 36 year old Dennis Aabo Sorensen from Denmark lost his left hand and some of his arm in a fireworks accident. Today, he is “feeling” objects again thanks to a robotic hand that is controlled by his mind and allows him the sense of touch. The device connects to both his brain and nerves in his upper arm and transmits signals from sensors in fingers of the hand directly to his brain. While wearing the artificial hand, he was able to differentiate between hard, soft, round, and square objects even while wearing a blindfold and earplugs over a 4 week trial of the device.
The device is controlled by the wearers mind and thoughts which has been done before, but this is the first time in neuroprosthetics sensory feedback has been restored and used by an amputee in real time to control an artificial limb. The researchers were able to adjust stimulation levels to correspond with the amount of pressure being applied to a digit, producing sensations ranging from the lightest touch to major pressure. The next step is to refine the electronic systems for sensory feedback to allow the device to become more portable. Researchers also need to develop the technology to raise awareness of the fingers angular movements. It is believed that the technology could be a step towards creating prostheses that allow the wearers to sense textures and temperature.
The Swiss study is the result of a collaboration called Lifehand 2, using a robotic hand, under development by several European universities and hospitals. A patient controls the movement of the hand with standard technology in which muscles in the residual limb activate mechanical parts on the prosthesis.
“I Could Feel Something I Had Not Been Feeling For 9 Years”
“It was quite amazing because suddenly I could feel something I had not been feeling for nine years,” Mr. Sorenson said. “The sensory feedback was incredible. You can feel round things and hard things and soft things. The feedback was totally new to me, and suddenly when I was doing the movements I could feel actually what I was doing, instead of looking at what I was doing.”
The hand was developed by Dr Silvestro Micera and his team at the Swiss Federal Institute of Technology, Lausanne, along with the The Sant’Anna School of Advanced Studies in Pisa, Italy. They were concerned about reduced sensitivity in the patient’s nerves, as he had not used them for nine years. but they found they were able to reactivate his sense of touch when he was wearing the prosthetic hand. They hope that by adding tactile functions to artificial limbs it would allow amputees to live completely unimpeded lives. The team behind the artificial limb said it would mean amputees could hold objects without having to watch their hands to detect the tightness of their grip.
Dr Alastair Ritchie, a lecturer in biomaterials and bioengineering at the University of Nottingham, said it was a key development for amputees being able to feel how tightly they were gripping objects, and to be able to adjust this depending on what they were holding. He said: “This is very interesting work, taking research in upper limb prosthetics into the next stage by adding sensory feedback. Upper limb prosthetics has long been a challenge for bioengineers – our hands are one of our principal interfaces with the world, and in recent years we have seen real advances.” He also added that the use of a sensor, connected to an electrode embedded in nerves, had to be managed carefully in the long term to prevent infection.
The Swiss institute said in a press release that the Dutch man was “the first amputee in the world to feel—in real time—with a sensory-enhanced prosthetic,” but other such trials are underway. The implants in one of Case Western’s subjects in Ohio, Igor Spetic, a 48-year-old man who lost his right hand in an industrial accident, has been in place now the longest.
Researchers said the development of a fully functional bionic hand is still some years away. Details of the Swiss implant are published today in the journal Science Translational Medicine.
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