ROBOTIC HAND

One thing is creating an exquisite robotic hand. One more is commanding it to do what you want. The challenge of sending the cue from the wearer's brain persists despite the development of hand-shaped prostheses that can bend each complex joint when instructed.

Researchers have now developed a system that allows amputees to control a robotic hand precisely by thinking about the movements they want to make with their fingers by intercepting signals from nerves in the arm. The interface, which amplifies a user's nerve signals via a series of microscopic muscle grafts, just passed its first human test. It converted the nerve signals into movements, and its accuracy remained consistent over time.

Most modern robotic prostheses function by capturing electrical impulses from muscles that have remained intact following an amputation from the skin's surface. By tensing the muscles still present in the forearm that would have controlled their fingers, some amputees can manipulate their mechanical hand. People who lack certain muscles can learn to move in less natural ways, as by flexing their upper arm muscles.

However, some configurations can be tricky. When a person's arm perspires, swells, or moves about inside the prosthesis' socket, an electrical signal is altered. Shriya Srinivasan, a biomedical engineer at the Massachusetts Institute of Technology, says that as a result, the devices need to be calibrated often, and many individuals feel that wearing a bulky robotic arm all day just isn't worth it.

Therefore, by coupling nerve signals to a muscle, researchers have attempted to strengthen them. Some researchers have redirected arm nerves into a chest muscle, where they have detected the potent electrical signal produced when someone contracts that muscle by imagining moving their hand.