Bionic fingertip allows amputee to feel texture

In a world first, an amputee has been able to feel smoothness and roughness in real-time with an artificial fingertip that was surgically connected to nerves in his upper arm, an advance that may lead to touch enabled prosthetics, scientists claim.
The nerves of non-amputees can also be stimulated to feel roughness, without the need of surgery, meaning that prosthetic touch for amputees can now be developed and safely tested on intact individuals, researchers said.
The research by a team at EPFL (Ecole polytechnique federale de Lausanne) in Switzerland and SSSA (Scuola Superiore Sant'Anna) in Italy provides new and accelerated avenues for developing bionic prostheses, enhanced with sensory feedback.

The amputee Dennis Aabo Sorensen is "the first person in the world to recognise texture using a bionic fingertip connected to electrodes that were surgically implanted above his stump," researchers said.
Nerves in Sorensen's arm were wired 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 translated into a series of electrical spikes, imitating the language of the nervous system, then delivered to the nerves.

Sorensen could distinguish between rough and smooth surfaces 96 per cent of the time.

In a previous study, Sorensen's implants were connected to a sensory-enhanced prosthetic hand that allowed him to recognise shape and softness.
This same experiment testing coarseness was performed on non-amputees, without the need of surgery.
The tactile information was delivered through fine needles that were temporarily attached to the arm's median nerve through the skin. The non-amputees were able to distinguish roughness in textures 77 per cent of the time.
The scientists tested this by comparing brain-wave activity of the non-amputees, once with the artificial fingertip and then with their own finger.

The brain scans collected by an EEG cap on the subject's head showed that activated regions in the brain were analogous.
The research demonstrates that the needles relay the information about texture in much the same way as the implanted electrodes, giving 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.
The research was published in the journal eLife.