It may sound like the stuff of science fiction, but the Rehabilitation Institute of Chicago says it's seeing success with what it calls the first “thought-controlled bionic leg.”

Zac Vawter, 31, an amputee, proved just how agile the device is by climbing 103 flights of stairs inside Chicago's Willis Tower.

Vawter, a former runner in college, lost his left leg above the knee in a 2009 motorcycle accident. Months afterward, the Seattle resident was connected to the Rehabilitation Institute of Chicago's Center for Bionic Medicine to participate in a research trial using the prosthesis.

What makes the bionic device, well, bionic is that it can read neural feedback as someone such as Vawter goes about his daily life. So when Vawter pushes down on the leg to stand, the leg pushes back to propel him up.

To demonstrate how well the device works, Vawter was one of almost 3,000 people who took on 103 floors in SkyRise Chicago, which has been dubbed the world's tallest indoor stair climb event.

(Outliers can attest to how impressive this feat was. We could barely make it to the top of the Statue of Liberty—and that's a mere 27 stories.)

The “thought-controlled” bionic leg reads neural feedback. Photo credit: REHABILITATION INSTITUTE OF CHICAGO

“With my standard prosthesis, I have to take every step with my good foot first and sort of lift or drag the prosthetic leg up,” Vawter said in a news release. “With the bionic leg, it's simple, I take stairs like I used to, and can even take two at a time.”