Nine years after an accident caused the loss of his left hand, Dennis Aabo Sørensen of Denmark has become the first amputee in the world to grasp objects and feel – in real time – with a sensory-enhanced prosthetic hand that has been surgically wired to nerves in his upper arm. He can even identify what he is touching while blindfolded. The revolutionary sensory feedback system in the Lifehand was developed by Silvestro Micera and his team at the EPFL Centre for Neuroprosthetics and SSSA in Italy.
“The sensory feedback was incredible,” reports the 36 year-old amputee, who lost his hand while handling fireworks during a family holiday. “I could feel things that I hadn’t been able to feel in over nine years.” In a laboratory setting, wearing a blindfold and earplugs, Sørensen was able to detect how strongly he was grasping, as well as the shape and consistency of different objects he picked up with his prosthesis. “When I held an object, I could feel if it was soft or hard, round or square.”
Micera and his team enhanced the artificial hand with sensors that detect information about touch. This was done by measuring the tension in artificial tendons that control finger movement and turning this measurement into an electrical current. But this electrical signal is too coarse to be understood by the nervous system, so – using computer algorithms – the scientists transformed the electrical signal into an impulse that sensory nerves can interpret. The sense of touch was achieved by sending the digitally refined signal through wires into four electrodes that were surgically implanted into what remains of Sørensen’s upper arm nerves.
Watch Sørensen feel in real-time with the bionic hand…