Amputee can feel again with new bionic hand

For the first time in nine years after his accident, left-handed amputee Dennis Aabo Sørensen from Denmark can feel objects in real-time with a sensory-enhanced bionic hand.

Silvestro Micera and his team at EPFL (Switzerland) and SSSA (Italy) created the prosthetic using sensory feedback technology that surgically wires nerves into his upper arm, and allows Sørensen to feel objects he's handling - the first amputee to do so.

Lifehand 2 published the study Feb. 5 in the "Science Translational Medicine," a collaboration between several European universities and hospitals. 

Ecole Polytechnique Fédérale de Lausanne said Sørensen could determine with his prosthetic how tight his grip was on an object, as well as its shape and consistency - all while wearing a blindfold and earplugs.

"When I held an object, I could feel if it was soft or hard, round or square," the 36-year-old said in a statement. 

In order to detect the touch sensation, Micera and others first measured the tension in the artificial tendons of the prosthetic and turned that tension into a measurable electric current. The electrical signal was then turned into a sensory impulse that the nerves could interpret using a series of algorithms. The refined signal traveled through wires leading to the four electrodes surgically implanted into Sørensen's arm nerves. Thomas Stieglitz's research group at Freiburg University (Germany) developed the electrodes that made this groundbreaking invention possible.

Stanisa Raspopovic, first author and scientist at EPFL and SSSA, did voice some of the scientists' initial concerns in the study.

"We were worried about reduced sensitivity in Dennis' nerves since they hadn't been used in over nine years," she said.

Although the electrodes were removed from Sørensen's arm one month after the surgery due to safety precautions, the scientists could not foresee any permanent nerve damage from them in the future.

This study is an important step toward a fully bionic-feeling hand, but won't be commercialized until the sensory technology is more fine-tuned and researchers understand the angles and movement of the fingers, the study's authors said.