Sponge makes robotic device a soft touch
 A simple sponge has improved how robots grasp, scientists from the University of Bristol have found.     Robot sponge. Image credit: Tianqi Yue This easy-to-make sponge-jamming device can help stiff robots handle delicate items carefully by mimicking the nuanced touch, or variable stiffness, of a human. Robots can skip, jump and do somersaults, but …