Source: Scientific American
Most bionic limbs are controlled by electrical signals generated by muscles moving near the attachment site. But when an arm is amputated above the elbow, the remaining muscles aren't enough to control every joint in an artificial hand. “The higher the amputation, the more joints you have to replace, and the fewer muscles you have to do it,” says Max Ortiz Catalán, a bionicist at Chalmers University of Technology in Sweden.