Scientists have developed a bionic fingertip that allows amputees to 'feel' different textures as if with a phantom limb, according to research published in the journal eLife today.
It’s common for people who lose a limb or part of a limb to feel their missing body part long after it's gone. These phantom limbs, which often cause their owners real pain, represent a neurological puzzle. But, as the inventors of the bionic fingertip realized, they may also represent an opportunity for restoring amputees’ sense of touch.
Previous studies by the same researchers showed that external devices connected to nerve endings could communicate information about shape and touch, but texture was harder to reproduce. Dennis Aabo Sørensen (pictured above) collaborated with the researchers to create and test the artificial fingertip. The research team implanted electrodes at the end of his arm and connected those to sensors in the fingertip. A machine pressed the fingertip across various rough and smooth surfaces, which sent tactile feedback through the sensors and into Sørensen’s arm. The feedback was amazingly clear: Sørensen could tell the difference between rough and smooth textures 96 percent of the time, even when he was blindfolded.
“The stimulation felt almost like what I would feel with my hand," Sørensen said in a press release. “I felt the texture sensations at the tip of the index finger of my phantom hand.”
The researchers also successfully tested their bionic fingertip on non-amputees, using electrical sensor caps to measure how the information was processed in their brains. (Click the image below to enlarge it.) Interestingly, while Sørensen successfully identified the texture the bionic fingertip was touching 96 percent of the time, the four non-amputee participants had a 77 percent success rate. The researchers did not speculate on the reasons for this gap.
“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," co-author Calogero Oddo said in the press release. "It will also be translated to other applications such as artificial touch in robotics for surgery, rescue, and manufacturing.”