Dennis Aabo Sørensen is the first amputee in the world to feel sensory rich information (in real time), thanks to a prosthetic hand hard-wired into the nerves in his upper arm.

Credit: Lifehand 2 / Patrizia Tocci

After nine years ago he lost his left hand, Dennis Aabo Sørensen got lucky. Silvestro Micera and his team at EPFL (Switzerland) and SSSA (Italy) developed a revolutionary sensory feedback system that allows Dennis not only to move his artificial hand and fingers, but also to feel through them. A prototype of this bionic technology was tested in February 2013 during a clinical trial in Rome – and it worked out just fine.

“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, 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 prosthetic. “When I held an object, I could feel if it was soft or hard, round or square.”

As my colleague Tibi Puiu wrote before, prosthetic arms (and legs, for that matter), have come a very long way. Cleveland researchers have already developed a prototype that can ‘feel’ pressure on the prosthetic, DARPA is working on solutions for veterans, and a joint team of scientists created a robotic arm that can be controlled through mind power.

Micera and his team enhanced the artificial hand with sensors that detect information about touch. In order to do this, they measured the tension in the artificial tendons that control finger movement and turning this measurement into an electrical current. Basically, they figured out a way to translate the body’s natural signals into an artificial language – and it worked like a charm.

“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 and scientist at EPFL and SSSA. These concerns faded away as the scientists successfully reactivated Sørensen’s sense of touch.

The clinical study is one of the first steps towards a true bionic arm – but researchers warn that a true sensory enhanced prosthetic arm is years away from hitting the shelves. The next step involves miniaturizing the sensory feedback electronics for a portable prosthetic. In addition, the scientists will fine-tune the sensory technology for better touch resolution and increased awareness about the angular movement of fingers.

Sørensen’s story is a pretty strange, yet fairly common one – he lost his left hand while handling fireworks during a family holiday. After this accident, he was rushed to the hospital where his hand was immediately amputated.

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