Harvard scientists sandwiched a layer of transparent rubber between two layers of a specially-made hydrogel. Electrical audio signals sent to the gel layers caused the rubber to vibrate and make sound.
Zhigang Suo and his team of Harvard scientists have created a prototype of an audio speaker made of transparent rubber and a saltwater-polymer hydrogel. The rubber was sandwiched between two sheets of gel, each of which was connected to copper electrodes. A computer sending audio signals through the electrodes caused ions to the gel layers to flow, and in response, the rubber layer vibrated at different frequencies, producing sound. In a video demonstration, the speaker plays music and other sounds while stretched over a computer screen.
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What’s the Big Idea?
Unlike electrical devices, which use electrons to carry charge, the human body uses ions to send signals to different parts of the body. It was this mechanism that inspired the stretchy speaker, believed to be the first of its kind. Besides serving as a sound-producing coating for computer or TV screens, the technology could also be incorporated into windows to make them soundproof. However, because hydrogels tend to dry out relatively quickly, Suo hopes to find alternate materials that conduct ions and last longer.