An amputee has become the first person on Earth to successfully identify texture using a bionic fingertip. The new unit stimulates his nerves, the team reported Tuesday in the journal eLife.
The bionic fingertip, which was developed by Silvestro Micera of the Swiss Federal Institute of Technology in Lausanne (EPFL), Calogero Oddo of the Sant’Anna School of Advanced Studies (SSSA) and their colleagues, was surgically connected to the nerves in the injured man’s upper arm and purportedly allowed him to feel smoothness and roughness in real time.
Furthermore, the study authors noted that the they have found a way to stimulate the nerves of non-amputees so that they could feel roughness without the need for surgery, which means that prosthetic devices could be safely tested on people without such injuries. They believe that their work may open up new avenues for the development of enhanced bionic prostheses.
“The stimulation felt almost like what I would feel with my hand,” the implant recipient, Dennis Aabo Sørensen, said in a statement. “I still feel my missing hand, it is always clenched in a fist. I felt the texture sensations at the tip of the index finger of my phantom hand.”
Research could lead to prosthetics with improved touch resolution
The researchers implanted electrodes above his injury and connected the device to nerves in his arm. A machine then controlled the fingertip’s movement over different pieces of plastic with different textures, and as it moves, the sensors generated an electrical signal.
That signal was translated into a series of electrical spikes designed to imitate the firing of sensory nerves. Sørensen correctly distinguished between rough and smooth surfaces 96 percent of the time, building on previous research where implants allowed him to recognize shapes.
The same texture-identification experiment was conducted, without the need for surgery, on non-amputees using needles that were temporarily attached to the arm’s median nerve. These individuals could determine whether a surface was rough or smooth 77 percent of the time, the EPFL and SSSA researchers added, and by studying the brain waves of these individuals, they may be able to improve touch resolution in prosthetic devices.
“This study merges fundamental sciences and applied engineering: it provides additional evidence that research in neuroprosthetics can contribute to the neuroscience debate, specifically about the neuronal mechanisms of the human sense of touch,” said Oddo. “It will also be translated to other applications such as artificial touch in robotics for surgery, rescue, and manufacturing.”