Robots have mastered picking and placing, welding, and similar tasks that can be precalibrated, but they cannot perform tasks that requite a sense of touch, such as "feeling" when a bolt's threads mesh before screwing it in. Even the most accurate robots today will strip the threads on bolts and otherwise damage items that require a sensitive tactile sense. Electrical engineers at the University of Illinois (Urbana-Champaign) say they are on the way to solving this problem. The team has created a prototype robot "skin" from a flexible polymer with multiple sensors that simultaneously assess shape, force, hardness, motion, temperature and thermal conductivity. Robots with a sense of touch are rare, but even those with touch sensors usually just have a single strain gauge, making it impossible for them to determine the hardness of an object or even how hard they are squeezing it. Applying the same pressure to different objects may cause the robot to drop one that is very hard and slippery or break another that is soft and fragile. The challenge is to enable the robot to sense the material from which the object is made so that it can adjust its grip accordingly.