A 31-year-old software engineer will attempt to make history on Sunday by climbing 103 flights of stairs in Chicago’s Willis Tower on his state-of-the-art-prosthetic leg. After losing his right leg in a motorcycle accident, Zac Vawter signed up to become a research subject at the Rehabilitation Institute of Chicago, helping to test a new kind of prosthetic controlled by his thoughts. The climb, called the “SkyRise Chicago,” is a fundraising initiative by the Institute and will feature almost 2,700 other climbers. However, researchers will be watching Vawter’s progress the closest. While most prosthetics are what the University of Michigan’s Daniel Ferris calls “fancy wooden legs,” Vawter’s bionic leg responds to electrical impulses in his hamstring, essentially allowing him to control it with his thoughts as he would his natural limbs. The $8 million project is funded in part by the U.S. Department of Defense.