Amputee receives first sensory-enhanced bionic hand

Dennis Aabo Sørensen from Denmark has became the first amputee to receive a bionic prosthetic hand with real-time sensory feedback. Engineering researcher, Silvestro Micera and his team at Ecole Polytechnique Fédérale de Lausanne (EPFL) and SSSA in Italy developed the arm that not only transmits feeling but also allows Sorensen to open and close the hand.

“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.”

Transneural electrodes surgically implanted into the ulnar and median nerves of Sørensen’s left arm, connect to sensors that measure tension in the artificial tendons that control finger movement. The measurement is then converted to an electrical current that is converted by computer algorithms into an impulse that sensory nerves can interpret.

The ultra-thin and precise electrodes, developed by Thomas Stieglitz’s research group at Freiburg University in Germany, made it possible to relay extremely weak electrical signals directly into the nervous system.

While the clinical study was a successful first step towards a bionic hand, the researchers say a sensory-enhanced prosthetic is years away. 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.
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