To say that robots don't have feelings is literal, as well as figurative. Not only can they not feel emotions such as love and rage and heartache, but they're numb on the outside too. They mostly interact with their environments through visual cues.

Unlike humans, they can't feel tactile cues such as temperature and pressure. A robot can't feel that a surface is dangerously hot. If it's about to crush something in its grip, it can't see this pressure until it's too late.

However, this is changing with an invention called E-skin. E-skin looks something like fishnet stockings, but thicker. It's composed of sensors laced onto a plastic film. Not only can E-skin detect temperature and pressure, but it's pliable. It can bend with the robot's finger joints and fold into crevices as small as the frown wrinkles on a humanoid robot face.

Tactile sensors already existed in some robots, but they'd been limited to small specialized clusters in part because they'd been made of material that would snap with any kind of bending. Though the E-skin's flexibility allows it to withstand the force of movement and creases, there's a downside to this flexibility too. The material is probably sturdy enough to last years if used gently, say in a home, but may not last a week if subjected to rough terrains.

Though the new E-skin is quite an improvement to the few clusters of tactile sensors of the past, it's hardly as sensitive as human skin. The E-skin can't sense pressure smaller than the weight of thirty pennies. Also, so far, it can detect only hot temperatures between 86 and 176 degrees Fahrenheit.