Robotic arm gives quadriplegic man a new sense of touch
In 2012, quadriplegic Jan Scheuermann used her own thoughts to control a robotic arm and feed herself a chocolate bar thanks to a system developed by researchers from the University of Pittsburgh and the University of Pittsburgh Medical Center (UPMC). Now, the same team has recreated the physical feeling of touch through a robotic hand, allowing a quadriplegic man to feel "his" fingers and hand for the first time in 10 years.
After first demonstrating their robotic arm in 2012, the team continued to improve the technology to extend the functional utility of the hand so that it approached the agility of a natural human limb. But although regaining movement is important, how objects feel in our hands also plays a crucial role, creating a feedback loop that allows us to adjust our grip and motion as required. Through further development of the robotic arm and brain computer interface (BCI), the Pitt-UPMC team was able to give 28-year-old Nathan Copeland, who was paralyzed in a car accident in 2004, the sensation of touch again.
Like Scheuermann's procedure, the arm was wired directly into Copeland's brain, allowing him to control it with the same kind of thought commands anyone would normally use. The difference in this case was that the electrical signals from the arm were transmitted through four tiny microelectric arrays implanted into the regions of the brain associated with feeling in individual fingers and the palm. The end result was the ability to feel pressure and how strong it was, although so far he hasn't been able to distinguish between different temperatures.
"I can feel just about every finger — it's a really weird sensation," explains Copeland, about a month after surgery. "Sometimes it feels electrical and sometimes it's 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."
As far as the research and technology has come, the Pitt-UPMC team acknowledges that there's still a long way to go on the road to eventually developing a system that moves and feels like the real thing. It's possible because the brain still remembers how to control the limbs – the injury just disrupts the connection between them.
"The most important result in this study is that microstimulation of sensory cortex can elicit natural sensation instead of tingling," says Andrew B. Schwartz, co-author of the study. "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."
The research was published in the journal Science Translational Medicine.