After getting caught in a blizzard while mountain climbing at age 17, Hugh Herr lost both his legs to severe frostbite. That hasn't slowed his pace.

Now at 51, the inventor and engineer is a member of IEEE and the co-director of MIT's Center for Extreme Bionics, where he designs prosthetic legs (including his own), along with feet, ankles, knees, and hips which push the limits of human capabilities. Herr's prosthetics have helped him to climb even more treacherous icefalls, and to continue clearing hurdles in the field of bionics.

In his own words:

Shortly after my amputation in 1982, I was fitted with prosthetic limbs. Their lack of technology shocked me, so I decided to design my own—ones that would enable me to return to mountain climbing. I quickly abandoned the notion that a prosthesis has to have a human shape and began optimizing function. I developed legs with adjustable heights so I could reach hand- and footholds.