An amputee may have felt something for the first time after his amputation. He's used an artificial fingertip to actually feel smoothness and roughness in real-time.
"The stimulation felt almost like what I would feel with my hand," said Dennis Aabo Sorensen, the amputee who used an artificial fingertip. "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."
In this latest study, the researchers wired nerves in Sorensen's arm to an artificial fingertip equipped with sensors. A machine controlled the movement of the fingertip over different pieces of plastic engraved with different patterns: smooth or rough. As the fingertip moved across the textured plastic, the sensors generated an electrical signal. This signal was then translated into a series of electrical spikes, imitating the language of the nervous system, then delivered to the nerves.
Sorensen could distinguish between the rough and smooth surfaces about 96 percent of the time. This is huge when it comes to providing amputees with robotic limbs that can actually function and act as real limbs.
This wasn't the only experiment that the researchers conducted, though. They also tested to see whether non-amputees could feel with the bionic finger. The tactile information was delivered through fine needles that were temporarily attached to the arm's median nerve through the skin. The researchers found that the non-amputees were able to distinguish roughness in textures about 77 percent of the time.
The new research demonstrates that the needles relay the information about texture in much the same way as implanted electrodes. This gives scientists new protocols to accelerate for improving touch resolution in prosthetics.
"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 Calogero Oddo of the BioRobotics Institute of SSSA, one of the researchers involved in developing the finger's technology. "It will also be translated to other applications such as artificial touch in robotics for surgery, rescue and manufacturing."
