Jesse Sullivan, a Tennessee power company lineman whose arms were amputated after he was electrocuted on the job, now has artificial limbs that let him rotate his wrists and upper arms, bend his elbow, grip with his hand, and, incredibly, feel. Sullivan's arm employs nerves from the chest muscle. When that muscle contracts, a myoelectric sensor atop his skin detects the contraction and sends it to an amplifier and then to a digital signal processor (DSP) in the Boston Digital Arm. The arm’s DSP interprets the signal and then sends a command
to the hand motor, which closes the hand.
(Source: Liberating Technologies)