Brain Health Blog

Oscar Pistorius, who lost both legs as an infant and then began running just 3 years ago, wants a spot in the 2008 Olympic 200m. Amazingly, at 21.58s he’s within 1 second of the qualifying time. He uses artificial limbs called Cheetahs (italicized to indicate speed), which, though they are just passive extensions of his legs attached below the knee, have elicited criticisms that they may give him an extra long stride and unfair advantage. Due to this ambiguity, the IAAF intends to block him from Olympic competition.

In actuality, people using artificial limbs have very few advantages. Even if Oscar’s Cheetahs really do help him sprint 200m, he couldn’t do it well in wind or rain, and activities as simple and critical to daily life as walking require substantially more energy. Existing prostheses generally suffer from being energy inefficient, and lack fine control and feedback.

Jeff Weber, working in the Biomechatronics Group within the MIT Media Lab, designs advanced prostheses to help amputees approach a normal life. His Active Ankle-Foot
Prosthesis uses an elegant system of springs to store energy with each stride, and motors to facilitate a natural and efficient gait. It is 20% more efficient than existing prostheses. Director of the lab, Hugh Herr, demonstrated the powered prosthesis for the first time just a few weeks ago.

This prosthesis will be a boon when it becomes available soon through Iwalk, but the Biomechatronics Group is already working on the next
generation of prostheses, which will interface with nerves for a more intelligent artificial limb. I learned from Jeff that it’s actually fairly easy
to interpret neural signals for this purpose – the real challenge is in accurately detecting them. To this end, one potential solution involves
injecting tiny capsules near the appropriate nerves to pick up and transmit a signal.

Think of the fun you could have with sensors that transmit your whims to nearby robotics… The peripheral nervous system goes wireless!