Picture yourself sitting in a fast car, boat, train, or plane and hearing almost no noise. Suppose that you and friends are in your house, apartment, or office and that the living or working space can unobtrusively determine where everyone is. Imagine that the poster or projection screen on your wall can play music and that the pad on your desk can hear you and your visitors. These and similar visions might soon come true with internally charged cellular polymer foams—a novel class of soft electromechanical transducer materials that can be used in sensors and actuators.
The word “material” stems from the Latin materia, which means “the wooden part of a tree.” An etymological relative is mater, that is, mother. Wood is not only one of the most ancient and still most widely used materials, it is also a natural cellular material. Cellular materials (or foams) consist of...
