Researchers have for the first time in the world successfully restored an amputee's sense of touch by connecting a prosthetic arm to the patients nervous system.
Dennis Aabo Sorensen is the first amputee in the world to feel sensory information - in realtime - with a prosthetic hand wired to nerves in his upper arm. Nine years after an accident caused the loss of his left hand, Sorensen could grasp objects intuitively and identify what he was touching while blindfolded.
Silvestro Micera and his team at EPFL (Switzerland) and SSSA (Italy) developed the revolutionary sensory feedback that allowed Sorensen to feel again while handling objects. A prototype of this bionic technology was tested in February 2013 during a clinical trial in Rome at Gemelli Hospital (Italy). The study appears in Science Translational Medicine,and represents a collaboration called Lifehand 2 between several European universities and hospitals.
"The sensory feedback was incredible," reports the 36 year-old amputee from Denmark. "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, Sorensen was able to detect how strongly he was grasping, as well as the shape and consistency of the objects he picked up with his prosthetic. "When I held an object, I could feel if it was soft or hard, round or square."
Electrical signal to nerve impulse
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. 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 Sorensen's upper arm nerves.
"This is the first time in neuroprosthetics that sensory feedback has been restored and used by an amputee in real-time to control an artificial limb," says Micera. "We were worried about reduced sensitivity in Dennis' nerves since they hadn't been used in over nine years," says Stanisa Raspopovic, first author. These concerns faded away as the scientists successfully reactivated Sorensen's sense of touch.
Connecting electrodes to nerves
On January 26, 2013, Sorensen underwent surgery in Rome at Gemelli Hospital. A specialised group of surgeons, led by Paolo Maria Rossini, implanted so-called transneural electrodes into the ulnar and median nerves of Sorensen's left arm. After 19 days of preliminary tests, Micera and his team connected their prosthetic to the electrodes - and to Sorensen - every day for an entire week.
The ultra-thin, ultra-precise electrodes, developed by Thomas Stieglitz's research group at Freiburg University (Germany), made it possible to relay extremely weak electrical signals directly into the nervous system. A tremendous amount of preliminary research was done to ensure that the electrodes would continue to work even after the formation of post-surgery scar tissue. It is also the first time that such electrodes have been transversally implanted into the peripheral nervous system of an amputee.
First artificial limb with touch
The clinical study provides the first step towards a bionic hand, although a sensory-enhanced prosthetic is years away from being commercially available and the bionic hand of science fiction movies is even further away. The next step involves miniaturising the sensory feedback electronics for a portable prosthetic. In addition, they will fine-tune the sensory technology for better touch resolution and increased awareness about the angular movement of fingers.
The electrodes were removed from Sorensen's arm after one month due to safety restrictions imposed on clinical trials, although the scientists are optimistic that they could remain implanted and functional without damage to the nervous system for many years.
See pic
HOW IT WORKS
Visual and auditory devices worn for undivided attention on touch sensations
Electrodes implanted directly into nerves in the upper arm
Prosthetic hand enhanced with sensors that detect information about touch
ELECTRICAL SIGNAL FROM SENSORS
This electrical signal is too coarse to be understood by the nervous system.
SIGNAL PROCESSING
Translation from electrical to a neurophysiological signal.
NERVE IMPULSES
This digitally refined new signal is transmitted through electrodes directly into the nervous system.
Dennis Aabo Sorensen is the first amputee in the world to feel sensory information - in realtime - with a prosthetic hand wired to nerves in his upper arm. Nine years after an accident caused the loss of his left hand, Sorensen could grasp objects intuitively and identify what he was touching while blindfolded.
Silvestro Micera and his team at EPFL (Switzerland) and SSSA (Italy) developed the revolutionary sensory feedback that allowed Sorensen to feel again while handling objects. A prototype of this bionic technology was tested in February 2013 during a clinical trial in Rome at Gemelli Hospital (Italy). The study appears in Science Translational Medicine,and represents a collaboration called Lifehand 2 between several European universities and hospitals.
"The sensory feedback was incredible," reports the 36 year-old amputee from Denmark. "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, Sorensen was able to detect how strongly he was grasping, as well as the shape and consistency of the objects he picked up with his prosthetic. "When I held an object, I could feel if it was soft or hard, round or square."
Electrical signal to nerve impulse
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. 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 Sorensen's upper arm nerves.
"This is the first time in neuroprosthetics that sensory feedback has been restored and used by an amputee in real-time to control an artificial limb," says Micera. "We were worried about reduced sensitivity in Dennis' nerves since they hadn't been used in over nine years," says Stanisa Raspopovic, first author. These concerns faded away as the scientists successfully reactivated Sorensen's sense of touch.
Connecting electrodes to nerves
On January 26, 2013, Sorensen underwent surgery in Rome at Gemelli Hospital. A specialised group of surgeons, led by Paolo Maria Rossini, implanted so-called transneural electrodes into the ulnar and median nerves of Sorensen's left arm. After 19 days of preliminary tests, Micera and his team connected their prosthetic to the electrodes - and to Sorensen - every day for an entire week.
The ultra-thin, ultra-precise electrodes, developed by Thomas Stieglitz's research group at Freiburg University (Germany), made it possible to relay extremely weak electrical signals directly into the nervous system. A tremendous amount of preliminary research was done to ensure that the electrodes would continue to work even after the formation of post-surgery scar tissue. It is also the first time that such electrodes have been transversally implanted into the peripheral nervous system of an amputee.
First artificial limb with touch
The clinical study provides the first step towards a bionic hand, although a sensory-enhanced prosthetic is years away from being commercially available and the bionic hand of science fiction movies is even further away. The next step involves miniaturising the sensory feedback electronics for a portable prosthetic. In addition, they will fine-tune the sensory technology for better touch resolution and increased awareness about the angular movement of fingers.
The electrodes were removed from Sorensen's arm after one month due to safety restrictions imposed on clinical trials, although the scientists are optimistic that they could remain implanted and functional without damage to the nervous system for many years.
See pic
HOW IT WORKS
Visual and auditory devices worn for undivided attention on touch sensations
Electrodes implanted directly into nerves in the upper arm
Prosthetic hand enhanced with sensors that detect information about touch
ELECTRICAL SIGNAL FROM SENSORS
This electrical signal is too coarse to be understood by the nervous system.
SIGNAL PROCESSING
Translation from electrical to a neurophysiological signal.
NERVE IMPULSES
This digitally refined new signal is transmitted through electrodes directly into the nervous system.
