Proto 2 is the name of the $55 million initiative of the Defense Advanced Research Projects Agency, or DARPA, to create a thought-controlled prosthetic arm.
[1] The next steps are to shrink the battery, develop more-efficient motors, and refine the bulky electrodes used to read electrical signals in muscles.
Researchers are experimenting with injectable myoelectric sensors (IMES) that detect muscle activity and wirelessly transmit commands to the prosthetic arm- in order to eliminate the bulkiness.
A wire coil wrapped over the shoulder supplies wireless power to the implants and relays signals to computers in the prosthetic that decipher the command and tell the arm to move.
The Proto 2 performs 25 joint motions: The shoulder and wrist are capable of roll, pitch and yaw, the elbow can flex, and the fingers and thumbs bend at each knuckle.