GelSight is an incredibly ultra-sensitive tactile sensor -- built for robots -- that essentially gives robots the ability to 'see' through their arms, allowing for more precise and complex robotic arm movements and functions.
The sensor works thanks to a slab of clear rubber coated on one side along with a layer of metallic paint. When the painted site is pressed against a surface, it adopts it shape. By looking through the unpainted side, the sensor's system can convert contours and lines into 3D images and feed them into the robot's control system.
The MIT researchers who developed the GelSight sensor system have already successfully demonstrated it identifying a hanging USB cable, grabbing it with its pinchers and then inserting it into the appropriate plug.