Researchers have created an artificial fingertip that can be surgically connected to nerves in the upper arm that amputees can use to feel relative roughness or smoothness. In early testing, it was connected to an amputee and also used by nonamputees to distinguish the coarseness of surfaces.
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| Dennis Aabo Sørensen--Courtesy of Ecole Polytechnique Fédérale de Lausanne |
Amputee Dennis Aabo Sørensen, who previously was connected to a sensory-enabled prosthetic hand, was the first person to use the bionic fingertip via the electrodes that are surgically implanted above his stump.
After being connected, a machine controlled the fingertip movement over pieces of plastic engraved with different patterns that were smooth or rough. As it moved over the textured plastic, the fingertip generated an electrical signal that was translated to the nervous system that imitates its usual activity.
He was able to accurately distinguish between rough and smooth surfaces 96% of the time, the researchers reported.
"The stimulation felt almost like what I would feel with my hand," said Sørensen about the artificial fingertip connected to his stump. "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 was also conducted with nonamputees with an attachment via fine needles that were temporarily attached to the median nerve in the arm through the skin. But the sensitivity wasn't as acute; nonamputees were able to distinguish roughness only 77% of the time.
"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," says Calogero Oddo of the BioRobotics Institute of the Scuola Superiore Sant'Anna in Pisa, Italy. "It will also be translated to other applications such as artificial touch in robotics for surgery, rescue, and manufacturing."
The SSA and the Ecole Polytechnique Fédérale in Lausanne, Switzerland, conducted the research as part of a broader collaboration; the research was funded by grants from the Italian Ministry of Health, the National Institute for Insurance against Industrial Injuries, the Wyss Center for Bio and Neuroengineering as well as the Swiss National Competence Center in Research in Robotics.
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