WASHINGTON — To feel what you touch — that’s the holy grail for artificial limbs. In a step toward that goal, European researchers created a robotic hand that let an amputee feel differences between a bottle, a baseball and a mandarin orange.
The patient got to experiment with the bulky prototype for only a week, and it’s far from the bionics of science-fiction movies. But the research released Wednesday is part of an effort to create more lifelike, and usable, prosthetics.
“It was just amazing,” said Dennis Aabo Sorensen of Aalborg, Denmark, who lost his left hand in a fireworks accident a decade ago. “It was the closest I have had to feeling like a normal hand.”
This isn’t the first time scientists have tried to give some sense of touch to artificial hands. A few other pilot projects have been reported in the U.S. and Europe. But this newest experiment, published in the journal Science Translational Medicine, shows Sorensen not only could tell differences in the shape and hardness of objects, he also could react and adjust his grasp.
“It was interesting to see how fast he was able to master this,” said neuroengineer Silvestro Micera of Switzerland’s Ecole Polytechnique Federale de Lausanne, who led the Swiss and Italian research team. “He was able to use this information immediately in a quite sophisticated way.”
Scientists have made great strides in recent years in improving the dexterity of prosthetics. The sense of touch has been a difficult challenge and is one reason that many patients don’t use their prosthetic hands as much as they would like.
First, doctors at Rome’s Gemelli Hospital implanted tiny electrodes inside two nerves — the ulnar and median nerves — in the stump of Sorensen’s arm.
Those nerves normally would allow for certain sensations in a hand. When researchers zapped them with a weak electrical signal, Sorensen said it felt like his missing fingers were moving, showing the nerves still could relay information.
Micera’s team put sensors on two fingers of a robotic hand, to detect information about what the artificial fingers touched.
“It is really putting the brain back in control of the system,” said biomedical engineer Dustin Tyler of Case Western Reserve University, who wasn’t involved with the work but leads a team in Ohio that recently created and tested a similar touch-enabled hand. “That’s an important step.”
