Amputee climbs Willis Tower with bionic leg

A 31-year-old man equipped with a mind-controlled bionic leg recently climbed the stairs to the top of Chicago’s Willis Tower (formerly known as the Sears Tower) for charity. Zac Vawter, who lost his right leg in a motorcycle accident, is the first person to climb that high with a bionic limb — thanks to an $8 million grant from the US Defense Department and assistance from MIT, Vanderbilt University and various other educational bodies.

The leg responds to electrical pulses from muscles in his hamstring. It weighs about 10lb and contains two motors, which drive a belt-and-chain system that swings it at the knee joint. Unfortunately, Mr Vawter will not get to keep the leg; it will stay behind in Chicago, where researchers will refine its steering and other components before taking it to market.