A robot equipped with a "bean bag" hand is capable of grasping and picking up all kinds of objects with ease, a U.S. researcher says.

The simple gripper is made of a bag of coffee grounds and a vacuum, co-developer Eric Brown of the University of Chicago says.

To pick something up, the bag of loose grounds first melds around the object. Then the vacuum it sucks air out of the spaces between grains, causing the gripper to stiffen and become a hard vice molded to the outline of the object, ScienceNews.org reported.

Because the gripper's bulb conforms to any shape evenly before the vacuum is applied, it can handle a wide variety of objects.

"Our goal was to pick up objects where you don't know what you're dealing with ahead of time," Brown says.

Traditional robot "hands" or grippers using two-finger pincers, or even human-like hands with fingers and multiple joints, have to deal with complex finger positioning and forces.

"One of the tricky things about picking up delicate objects is that you have to know how much pressure to apply: too little and you drop the object; too much and you break it, says mechanical engineer Peko Hosoi of MIT, who was not involved with the new study. "This new gripper works by exactly conforming to the shape of the object so you can manipulate items with very little pressure -- and without requiring feedback from sensors.

"This could be game-changing technology," he says. "The idea is so simple, yet effective and robust."