Prosthetic (artificial) limbs that assist people who have lost an arm or leg have existed for centuries. The Greek historian, Herodotus, writes of a Persian soldier who cut off his foot to escape from his captors' chains and replaced it with a wooden leg. From wood to iron to lightweight plastic and metal, prosthetics have come a long way since ancient times.
At a recent Bionics conference in Washington D.C, Professor Todd Kuiken from Chicago demonstrated robotic arms that are controlled by the mind. This is no different from how most of us pick up a book or paper where our thoughts are converted to action!
Who needs prosthetic limbs? Some people are born with birth defects where an arm or leg is not fully developed. But the biggest use of prosthetics is among war veterans -- people who have had a limb amputated after it was severed in the battlefield. As a matter of fact, research in prosthetic limbs started in earnest in 1945 after World War II.
Lets start with how a normal limb works. When you want to lift a book, your brain sends an electrical command down your spinal cord. From here, the message travels through peripheral nerves to muscles that control your hand movement. The muscles contract or relax to perform the function -- in this case grasping a book and lifting it up.
Now imagine what would happen to this information pathway if the limb was amputated. The peripheral nerves would still carry electrical command signals from the brain, but the signals would meet a dead end and never reach the amputated muscles.
Hope For Many..
Dr. Kuiken had an idea - what if the peripheral nerves were moved to a muscle in the healthy part of the patient's arm, shoulder or chest muscle. The prosthetic limb could be connected to this new muscle through sensors on the skin and would respond just like a regular arm. According to Dr. Kuiken - "If you touch the person on this new skin, they feel their missing hand".
The end result is that just by thinking of moving the amputated arm, a patient causes the prosthetic arm to move instead. There is more work to be done such as getting the robotic arm to detect sensations such as heat or cold and send the signal back to the brain. Researchers around the world are working on making the prosthetic arm more life-like but this technology is already giving hope to the many disabled war veterans.