DARPA has funded many exciting projects in the past. Their latest project involves using a brain controlled robotic arm to help a paralyzed man, Nathan Copeland, feel again. To pull this off, the man underwent a surgery to have 2 micro-electrode arrays placed in his sensory cortex. These were then connected to a robotic arm.
The arm has torque sensors to detect when pressure is applied and convert the sensations into electrical signals. These signals are then sent to the arrays installed in Nathan’s brain. He can tell which of the fingers are touched each time.