Mind over matter? Here’s the story: Zac Vawter’s new leg is a loaner – it’s a research vehicle actually – that only he can drive. Like a test pilot who travels the sky steering a state-of-the-art machine, Zac has been maneuvering his innovative leg for a few years now.


Zac’s bionic leg – Reuters photo

He’s the first person to make it move by exerting mind over matter. The techs help him hook it up – and then he uses mind control to make it work.


Reuters photo

Here’s some footage showing Zac and his leg in action. (sorry about the commercial that precedes the piece)

What you’re looking at is the world’s first successful bionic leg. It is totally controlled by Zac’s thoughts and the nerves that deliver his movement messages to the leg’s sensors. When Zac heard about what the research scientists were trying to do, he journeyed from his home on the west coast to Chicago to volunteer. Zac, from the WSJ:

“It’s night and day. Going upstairs with my normal prosthetic, my sound leg goes up first for every step. With this I go foot-over-foot up the stairs and down the stairs.”


Reuters photo

What does it take to be the first person to control a smart prosthetic by brain signals alone? Here’s one way of looking at it, from Futurescope:

“The act of walking may not seem like a feat of agility, balance, strength and brainpower. But lose a leg, as Zac Vawter did after a motorcycle accident in 2009, and you will appreciate the myriad calculations that go into putting one foot in front of the other.”

The fact he can walk so normally is truly amazing. What the video doesn’t show is the enormous effort that went into all of this – thousands of hours spent with Zac test piloting his prosthetic and the researchers at the Rehabilitation Institute of Chicago perfecting their prototype. All of it funded by the US Army, with the hope that the 1200 wounded warriors who’ve lost a leg in combat can follow in Zac’s footsteps. Add to that a million civilians missing part of a lower limb and you get a sense of the importance of this scientific breakthrough.


WSJ photo by Andrew Nelles

Below is a simple animation of how the bionic leg works:

Marshal Gerometta photo

Chicago’s Willis Tower by Marshal Gerometta


To show you what kind of stuff Zac is made of, last year he took an earlier version of the bionic leg on a climb up 103 flights of stairs to the top of Chicago’s Willis Tower. That’s a challenge that many two-legged folks would find hard to meet. But Zac has grit, and he’s determined to make this new leg work, just as much as the scientists and engineers who created the bionic marvel.

Zac’s climb set a world record. In the picture below, the man behind him with the big smile is his dad.

AP photo

AP photo


Reuters photo

This  article and another describe the science in more detail. What I found fascinating was that up until now, when a leg was amputated doctors would let the nerves that sent messages to the foot and ankle die. But a novel surgery technique sends those nerves along a new pathway to muscles in the thigh. That’s the first step in making it possible for Zac to exercise mind control to move the bionic leg.


Dr. Levi Hargrove – Reuters photo

Dr. Levi Hargrove, an electrical engineer and research scientist at the Rehabilitation Institute of Chicago explains:

“We kind of unplugged one little tiny nerve that went into the hamstring muscle and we plugged in a bigger nerve, the tibial nerve, that would have gone down and connected to muscle that would have lifted his foot up into the air.”

So the same signals from the brain that would go to the foot now go to the thigh and, through sensors attached to a small computer in the bionic leg, the artificial limb can read and interpret those impulses through a process called pattern recognition. In this case, pattern recognition happens as quickly as if the limb was part of Zac – and in a way, it is. That’s why his gait is so natural.

The same facility has successfully made robotic arms, but for artificial legs the stakes are much higher. Dr. Hargrove:

“When controlling arms, if you make a small mistake the elbow might flex a little more than you intended it to, but when controlling legs, if you make even a little mistake, it could cause a patient to fall.”

We take so much for granted. When your body works the way it should, you never think about what makes your feet behave correctly as you go up and down stairs – you just do it. Until Zac’s bionic leg was developed, the best prosthesis available was not a lot more advanced than the first wooden leg. Now, a scientific and engineering breakthrough has opened a door to new possibilities. And for people like Zac, the chance to get closer to the way things used to be.


Chicago Tribune photo

So what do you think? Leave a comment and let me know.