Hugh Herr was 17 years old when he designed his first prosthetic leg, just months removed from a brush with death and fresh off a grueling period of rehab. At the time, Herr was an unlikely engineer. An academic underachiever in high school, he'd been more attracted to mountain climbing than to physics. But in June of 1982, wearing two crude prosthetic limbs, he got the itch to resume some semblance of his old life.

"I wanted to design limbs so I could return to mountain climbing," he recalls. [Read the rest of this article.]