Bionic hand allows amputee to feel lifelike sensation

An international team of scientists have created a bionic hand which allows the amputee to feel lifelike sensations from their fingers.

Dennis Aabo from Denmark received the hand, which was connected to nerves in his upper arm, following surgery in Italy.

Dennis Aabo, who lost his left hand in a firework accident nearly a decade ago, said the hand was “amazing”.

In laboratory tests he was able to tell the shape and stiffness of objects he picked up, even when blindfolded.

The details were published in the journal Science Translational Medicine.

The team carried out the research project, which included robotics experts from Italy, Switzerland and Germany.

“It is the first time that an amputee has had real-time touch sensation from a prosthetic device” said Prof. Silvestro Micera from the Ecole Polytechnique Federale de Lausanne and Scuola Superiore Sant’Anna, Pisa.

The scientific advance here was not the hand itself, but the electronics and software that enabled it to give sensory feedback to the brain.

Prof. Silvestro Micera and his team added sensors to the artificial hand which could detect and measure information about touch. Using computer algorithms, the scientists transformed the electrical signals they emitted into an impulse that sensory nerves could interpret.

During an operation in Rome, four electrodes were implanted onto nerves in the patient’s upper arm. These were connected to the artificial sensors in the fingers of the prosthetic hand, so allowing touch and pressure feedback to be sent direct to the brain.

Dennis Aabo, 36, a property developer, spent a month doing laboratory tests, firstly to check the electrodes were functioning, and then with these fully connected to the bionic hand.

He said: “The biggest difference was when I grabbed something I could feel what I was doing without having to look. I could use the hand in the dark.

“It was intuitive to use, and incredible to be able to feel whether objects were soft or hard, square or round.”

The bionic hand is still a prototype, and due to safety restrictions imposed on clinical trials, Dennis Aabo required a second operation to remove the sensors.

Professor Paolo Rossini, neurologist, University Hospital Agostino Gemelli, Rome, said a lot of pre-training was done involving surgery on pigs, and with human cadavers, to ensure they knew exactly how to attach electrodes to the tiny peripheral nerves in the upper arm.

Another member of the team, Dr. Stanisa Raspopovic said: “It was a very exciting moment when after endless hours of testing….Dennis turned to us and said with disbelief, <<This is magic! I can feel the closing of my missing hand!>>”

The international team is now working on how to miniaturize the technology so that it could be used in the home.

“We must get rid of the external cables and make them fully implantable” said Prof. Thomas Stieglitz, University of Frieburg, Germany, whose laboratory created the ultra-thin implantable electrodes.

There is no precise timetable, but scientists think it could be a decade before a sensory feedback bionic hand is commercially available.

And they believe it may pave the way for more realistic prosthetic devices in the future which can detect texture and temperature.

But it will undoubtedly be very expensive, well beyond the means of most patients. And artificial hands still lack the precision and dexterity of the real thing.

The super-functioning bionic hand of science fiction films remains the stuff of fiction.

Nonetheless, Dennis Aabo, who now has his old prosthesis back, is ready to swap it for the bionic hand in any future trial.

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