European researchers have created a robotic hand that gave an amputee a sense of touch he had not felt in a decade. With the artificial limb, the patient could “feel” the different objects – such as a bottle, some cotton or a piece of fruit – and was able to intuitively adjust his grasp.
Amputee Dennis Aabo Sorensen lost his left hand in a firework accident.
“That was truly amazing to suddenly feel something after nine years,” he said. “Because suddenly my hand is talking to the brain again, if you wish, and that was incredible.”
Doctors at Rome’s Gemelli Hospital implanted tiny electrodes inside two nerves in the stump of Sorensen’s arm. When the nerves were stimulated with a weak electrical signal, Sorensen said it felt like his missing fingers were moving, which meant the nerves still worked.
The team put sensors on two fingers of a robotic hand, to detect information about what the artificial fingers touched. This information was sent to Sorensen’s brain.
“The electrodes are really selective, in the sense that they are able to achieve a very precise contact with small fascicles in the nerves. This is crucial to have close to natural sensations,” said Silvestro Micera, Associate Professor of Biomedical Engineering at the Swiss Federal Institute of Technology in Lausanne and University of Pisa.
This latest experiment is among the most advanced in the prosthetics field, essentially creating a loop that lets the robotic hand rapidly communicate with Sorensen’s brain so he could feel and react in real time. But what kind of surgery does it require?
“So the surgeon had to first create a surgical theatre where the two nerves were clearly put in evidence. Then he had to open the sheet around the nerves, identify individual fascicles and then he had to insert the electrodes properly,” said Paolo Maria Rossini, Chief Neurologist at Rome’s Gemelli Hospital.
Though it will take years of additional research before an artificial hand that feels becomes a reality, these new tests are part of a major effort to create more lifelike and usable prosthetics.