Science | Bionic hand restores feeling to amputee
A Danish man has become the first amputee in the world to feel sensation in an artificial hand thanks to groundbreaking new research conducted by Silvestro Micera and his team at the Swiss-based technology institute EPFL.
Since losing his hand nine years ago Dennis Sørensen has relied on a prosthetic for grasping objects. However, for the first time in almost a decade he has been able to temporarily feel the objects he grasps thanks to a sensory enhanced artificial hand that was surgically wired to the nerves in his upper arm.
The new prosthesis works using electric sensors attached to the fingertips that can detect touch; the information relayed as electric signals to artificial tendons controlling the movement of the fingers. A computer located in the hand tunes the electrical current into an impulse sent down fine wires to four electrodes connected to peripheral nerves in the amputee’s arm, which in turn form a connection with the brain, allowing the patient to experience sensory feelings comparable to those felt by a normal hand.
During a four week clinical trial Sørensen was subjected to a series of laboratory tests focusing on the efficacy of the device once the electrodes were connected to the bionic hand. Sørensen was blindfolded and made to wear earplugs during this secondary testing to prevent visual and auditory cues influencing the results. Results showed that while wearing the artificial hand Sørensen was able to distinguish between hard, intermediate and soft objects, whilst additionally having the capability to identify the shapes of the objects he was touching. He was also able to detect how strongly he was grasping, a characteristic unheard of with previous prosthetics.
“I could feel round things and hard things and soft things, and the feedback was totally new to me. And suddenly when I was doing some movements; I could feel what I was doing instead of actually looking at what I was doing.”
The creation of a prototype prosthetic hand that can feel sensory rich information in real time presents a remarkable step forward for the construction of future artificial limbs. The next step for the creators of this device is to miniaturise the electronics required in its function, in order to create a portable and discrete prosthetic which could present a viable permanent option for patients and a very real prospect for the future of limb replacement.