Engineers claim to have created the world’s first prosthetic hand that allows amputees to regain a realistic sense of touch.
A team of Swiss and Italian researchers have developed a device that converts information about how the artificial hand is operating into electrical signals that allow the nervous system to feel the shape and texture of an object in real time.
The engineers now hope to adapt the technology, which relies on a series of ultra-thin, ultra-precise electrodes implanted into the arm, for a more user-friendly prosthetic with better movement capabilities, paving the way for the first fully functional bionic hand.
‘This is the first time in neuroprosthetics that sensory feedback has been restored and used by an amputee in real-time to control an artificial limb,’ said Silvestro Micera, who led the team at the Swiss Federal Institute of Technology in Lausanne (EPFL).
The prosthetic was tested by a man whose hand was amputated following a fireworks accident, 36-year-old Dennis Aabo Sørensen from Denmark. ‘The sensory feedback was incredible,’ he said. ‘I could feel things that I hadn’t been able to feel in over nine years.’
In a laboratory setting wearing a blindfold and earplugs, Sørensen was able to detect how strongly he was grasping objects, as well as their shape and consistency of different. ‘When I held an object, I could feel if it was soft or hard, round or square,’ he said.
The technology works by measuring the tension in artificial tendons that control finger movement. This data is turned into electrical signals that are then processed using computer algorithms to create impulses that can be read by the nervous system, sent through four electrodes implanted into what remains of the upper arm nerves.
The electrodes, developed at Freiburg University in Germany, make it possible to relay extremely weak electrical signals directly into the nervous system, even though the nerves had not been used for nine years.
As the trial was the first time such electrodes had been transversally implanted into the peripheral nervous system of an amputee, large amounts of preliminary research was done to ensure the electrodes would work after the formation of post-surgery scar tissue.
The next step will involves miniaturising the sensory feedback electronics for a portable prosthetic, and fine-tuning the technology for better touch resolution and increased awareness about the angular movement of fingers.
The electrodes were removed from Sørensen’s arm after one month due to safety restrictions imposed on clinical trials, but the scientists believe the implants could remain functional without damage to the nervous system for many years.
Bionic limbs have seen dramatic improvements in realistic function in recent years. The UK’s first prosthetic arm controlled directly by the brain was implanted in a soldier last year.