Hugh Herr, the head of the MIT Media Lab's Mechatronics Group, isn't just the creator of the PowerFoot BiOM, an amazing lower-leg robotic replacement. He's also a dedicated user. Herr lost both his legs at age 17 after getting trapped in a New Hampshire blizzard while hiking. Many surgeries later, the frostbite and damaged tissue were deemed too severe for repair, and both his legs were amputated below the knee.
The loss of his legs seems to have spurred Herr on to impressive heights. He attended college, then received degrees from Harvard and MIT before landing at MIT's prestigious Media Lab, a group that amazes us on a regular basis. His new task: create a set of prosthetics that would allow him to return to his passion, mountain climbing. (Check out a great interview with him over at NPR.)
The PowerFoot BiOM isn't just notable because of the story behind it; this is an outrageously advanced bionic leg and foot. Rather than merely acting as a spring, like Oscar Pistorius's Cheetah legs, the PowerFoot BiOM actually senses your environment and reacts accordingly. "The reflexive action in the PowerFoot," says iWalk, "returns 100% of the energy of a biological limb while accommodating for real time terrain changes, thus normalizing the amputees gait dynamics." It uses a dedicated spring to simulate the motion of the calf muscles and Achilles tendon, rather than relying on the entire leg as a counterbalance. That means walking feels like, well, walking. You can see it better in this video.
This is a truly robotic leg, taking in 250 points of data per step and analyzing them instantaneously to figure out how best to respond--how much to extend, how much to retract, how much to twist. And yes, they've allowed Herr to return to climbing--he further modified the PowerFoot BiOM to be smaller, with no heel (which he says he doesn't need for rock-climbing) and an optimized angle, unlike anything a human foot would be capable of. A bionic foot designed by a biomechanics wizard who also happens to be an amputee himself--that's the foot I want.
Current status: The PowerFoot BiOM is in the early stages of market release, but is definitely available.
Runner-up: Oscar Pistorius's Cheetah prostheses are a close runner-up, but they're limited-use legs and I don't even like running with two regular legs.