Balloon filled with ground coffee makes ideal robotic gripper. The gripper uses the same phenomenon that makes a vacuum—packed bag of ground coffee so firm; in fact, ground coffee worked very well in the device. But the researchers found a new use for this everyday phenomenon: They placed the elastic bag against a surface and then removed the air from the bag, solidifying the ground coffee inside and forming a tight grip. When air is returned to the bag, the grip relaxes.
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