Once reserved for sci-fi heroes and far-fetched television shows, bionic arms that can communicate with the brain are under development at Lawrence Livermore Lab and five years away from human testing. While a robotic arm conjures images of superhumans able to throw boulders like pillows, researchers are serious about recreating sensations that many take for granted: to feel the skin of a significant other, the texture of a fine linen or the cool water of a babbling brook.