 This is accomplished by copying human skin tissue and then tying it down to the artificial material that makes up the underlying face bones, if you will, of the robot's visage. Those tie-downs are made of elastin and collagen. They're essentially ligaments. The end result isn't something resembling a young and brawny Arnold Schwarzenegger, but the skin more easily moved with the robot's movement, unlike a synthetic covering. And if it did tear, it healed itself.