Prosthetic legs have gotten smarter and smarter thanks to advanced sensors and lightweight motors, but this week they're getting their biggest overhaul yet: the latest bionic leg can be controlled entirely by its wearer's mind. Though the mind-controlled prosthetic leg has been in the works for four years now, the research team behind it has only today published the details of its development, which are appearing in a paper in The New England Journal of Medicine.
The work comes out the Rehabilitation Institute of Chicago (RIC), which has a center dedicated to researching bionic medicine. The institute says that the leg can naturally switch between different types of movements simply by having its wearer think about them. "The bionic leg allows me to seamlessly walk up and down stairs and even reposition the prosthetic by thinking about the movement I want to perform," Zac Vawter, who tested the bionic leg, says in a statement. "This is a huge milestone for me and for all leg amputees."
"A mistake or error ... could be potentially catastrophic."
Though mind-controlled arms are already available, making a mind-controlled leg is an entirely different matter. "If there is a mistake or error that could cause someone to fall, that could be potentially catastrophic," Levi Hargrove, the project's lead researcher, tells NBC News. "We want to avoid that at all costs." But the mind-controlled leg appears to be operating smoothly. Last year, the research team publicized its progress after Vawter, while wearing the leg, climbed the full 103 floors of Chicago's Willis (née Sears) Tower.
The technology works much in the same way that researchers have been able to build bionic arms: Nerves heading toward a patient's damaged muscle are rewired onto healthy muscle, and a sensor is placed nearby to read what the nerves are saying. The bionic leg is then able to take that information and turn it into whatever action that its wearer originally conveyed through thought.
The RIC was given $8 million in funding from the US Army to work on creating the mind-controlled bionic leg. Defense arms of the US government have been interested in advancing prosthetics for some time now, particularly as a way to help injured veterans, and this isn't the only defense-funded project at the RIC. The RIC has also received funding from DARPA for improving the overall speed of neural interfaces — something that should help the RIC's bionic leg, as well as DARPA's own mind-controlled bionic arm.
The RIC hopes to have its bionic legs available for anyone to test within the next five years. Of course, cost may be a big issue, but Hargrove says that they're doing their best to keep the price down. "We are leveraging developments in related industries to make sure we use low-cost components whenever possible," he tells NBC News, which notes that bionic arms can run anywhere from $20,000 to $120,000.
"It makes a phenomenal difference."
For now, Vawter is the only person wearing one the RIC's mind-controlled bionic legs. But if the leg works as well as he says it does, it should be a marked improvement over existing technology once it leaves the lab. He tells NBC News, "It makes a phenomenal difference."