Read any science fiction and you’ll know that robots themselves can’t feel. But in a paper published this week from the University of Pittsburgh, researchers have shown that a mind-controlled robotic arm can help paralyzed patients regain sensation in their limbs.
Using a brain-computer interface, which has been shown to give patients the ability to move robotic extensions in past experiments by this UPitt team and others, is important for allowing a person to perform simple functions. But with this new technology, the arm can interact with its environment in ways comparable to a human arm, notably allowing the operator to "feel" pressure in the form of an electronic stimulus.
The robotic arm, developed at Johns Hopkins with a control system from Blackrock Microsystems, not only receives outputs from the brain, but it sends them back to a microelectrode array implanted in the brain’s sensory cortex. The arrays are dime-sized and placed in the regions where the patient would feel from areas on his or her hand.
"The most important result in this study is that microstimulation of sensory cortex can elicit natural sensation instead of tingling," study co-author Andrew Schwartz said. "This stimulation is safe, and the evoked sensations are stable over months. There is still a lot of research that needs to be carried out to better understand the stimulation patterns needed to help patients make better movements."
Test patient Nathan Copeland, who has a spinal cord injury leaving him quadriplegic, explained what it’s like to have the implants in place:
"I can feel just about every finger--it's a really weird sensation," Mr. Copeland said about a month after surgery. "Sometimes it feels electrical and sometimes its pressure, but for the most part, I can tell most of the fingers with definite precision. It feels like my fingers are getting touched or pushed."