US scientists have reported massive advances in bionic hands, which have restored a sense of touch in two patients for a period of more than a year. The study, published in Science Translational Medicine said the artificial hand has sensors that are used to send signals directly to the nerves. In the meantime, a Swedish team has made a different breakthrough in artificial limbs; they have been able to anchor bionic arms directly on to the bone in order to improve control.
Igor Spetic, who lost his right hand in an accident four years ago, was fitted with a bionic substitute, but unfortunately it was incapable of feeling the world around him. He had to cautiously watch whatever he was doing and then judge visually whether he was squeezing too firmly.
The team at Case Western Reserve University had attached sensors to the bionic hand and during surgery, fitted “cuffs” in the region of the remaining nerves. These were then capable of delivering electronic stimulation. The scientists were able to send different patterns of electronic stimulation to the nerves via a computer. These electronic patterns were interpreted by the patient’s brain as different sensations. The sensations were then “mapped” by the team to 19 separate locations on the hand and matched the sensors to the different electronic patterns of stimulus.
From there, they then moved to textures and pressure. Now Mr Spetic can tell, whilst blindfolded, whether he is handling different things, like Velcro or paper. He has now been using the device for two-and-a-half years. Mr Spetic said: “I would love to feel my wife’s hand, just to hold hands would be the ultimate.”
Lead researcher Prof Dustin Tyler said “We believe within five to 10 years we will have a system completely implanted so we would see a person in the morning, they would have the procedure to put electrodes on each nerve and a device for their pocket, so that when they turn it on they can feel their hands.”
The modified hand had the added bonus of eliminating “phantom limb pain”, this is when patients feel pain from the part of the body that is no longer there.
Across the pond, in Sweden, scientists at Chalmers University of Technology say they have implanted the first bone-anchored bionic arm. This technique is known as “osseointegration”; connecting the arm directly to the bone, nerves and muscles in the residual stump of the patient’s arm.
Dr Max Ortiz Catalan said: “We have used osseointegration to create a long-term stable fusion between man and machine, where we have integrated them at different levels…The artificial arm is directly attached to the skeleton, thus providing mechanical stability…Then the human’s biological control system, that is nerves and muscles, is also interfaced to the machine’s control system…Reliable communication between the prosthesis and the body has been the missing link for clinical implementation of neural control and sensory feedback, and this is now in place.”
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[Image via technologyreview]