When Dennis Aabo Sorensen lost his left hand 10 years ago while handling fireworks, it was safe to assume its sense of touch went with it.
But with the aid of new bionic technology, the 36-year-old once again knows what it feels like to grasp a ball, or pick up an object using his left hand.
Sorensen, a real-estate developer in the Danish city of Aalborg, recently made headlines when he became the first in the world to test a prototype prosthetic hand that allowed him to identify objects he was touching while blindfolded.
"I was totally amazed because suddenly I could feel something that I hadn't been feeling for almost 10 years," Sorensen says.
"The first thing was this baseball that they put in the prosthetic hand, and suddenly I could tell that I was holding a round piece -- a kind of a hard ball. So that was so incredible to have that feeling again."
Getting Back In Touch
After he lost his hand, Sorensen was fitted with a conventional prosthetic that detected muscle movement in his left limb and allowed him to open and close his hand and to hold onto objects.
But he could not feel what he was trying to grasp and had to keep an eye on his prosthetic to avoid crushing whatever object he was holding.
That changed about a year ago, when a group of surgeons and neurologists tested their new bionic prototype on Sorensen during a monthlong clinical trial in Rome. They published the study last week in the journal "Science Translational Medicine
Professor Silvestro Micera and his team surgically implanted electrodes into the nerves of Sorensen's left arm, and connected these electrodes to touch sensors in an artificial hand. Computer algorithms transformed the electrical signals from the sensors into an impulse that the nerves could detect.
Sorensen says his family "thought it was pretty cool that I had to go to Rome and do this experiment. My three boys called me the cable guy because of all the wires coming out [of my arm]."
During the clinical study, the artificial limb was connected to the electrodes every day for an entire week. Sorensen was able to control how forcefully he grasped different objects and feel their shape and consistency.
Still Just Out Of Reach
Researchers say this was the first time in neuroprosthetics that "sensory feedback has been restored and used by an amputee in real time to control an artificial limb." But they also note that, while a major advancement, a "sensory-enhanced prosthetic is years away from being commercially available."
Sorensen says he is ready to contribute to future research, acknowledging that his psychological strength was an asset for the study.
"This kind of experiment is pretty tough because [of the] long working days. You have to be in the center of between 50 to 60 people [who] have to get a lot of data out of you," he explains.
"Also, to do the implants and make the surgery and take [the electrodes] out, that's two big operations in 30 days. So you have to be fit in your mind and in your body as well."
Asked whether it was tough to experience touch again from his left hand, only to lose it again when the prototype was removed, the Dane says, "That's true, they took it away from me again, but in an experiment like this you know that's not going to be forever."
"But this is a big step towards the scientist [being able] to get a final product. And that would be amazing not only for me, but also for any other [person] in my kind of situation," Sorensen adds.
"Because of this breakthrough that we achieved one year ago, I'm positive that you will see a prosthetic hand like this on the market, available for people, in the years to come."