The two men told researchers at Case Western Reserve University that wiring some of their remaining nerves to a robotic arm — albeit only during visits to a lab — felt more like grasping objects with their own hand than with a tool.
“This feels like normal sensation,” one of the men, Igor Spetic of Madison, Ohio, said in an interview.
When researchers touched different spots on his artificial hand, “sometimes it felt like a cotton ball,” he said. “Sometimes like sandpaper.”
An unexpected benefit: The phantom pain both men have felt since losing their limbs in industrial accidents has nearly disappeared since they began the experiment, the researchers reported Wednesday in the journal Science Translational Medicine.
It will take years of additional research before robotic hands really let people feel what they touch. But the new research is an important step, said Dr. Michael Boninger, who directs the University of Pittsburgh Medical Center‘s rehabilitation institute and wasn’t involved with the experiments.
Beyond better function, getting feedback from the limb “would be a spectacular thing to be able to have, that you feel like the arm is your own,” he said.
People with natural limbs take for granted the intuitive control that a sense of touch allows. Reach for something and your hand naturally grasps with just enough force to hang on. But users of prosthetic hands have to watch carefully every motion, judging by eye how tightly to squeeze so they don’t either drop something or crush it. Consequently, many amputees abandon prosthetic hands, or don’t use them as much as they’d like.
Here’s how it works: The team at Case Western and the Cleveland Veterans Affairs Medical Center implanted electrodes around three nerves in the stump of the men’s arms.