Ionic Conductors Diagram (image) Harvard University Caption To make the speaker, a membrane of transparent, insulating rubber is sandwiched between two layers of transparent, conductive gel. The electrical connection to the power source is established outside of the active region of the device, where it does not need to be transparent. Credit Image courtesy of Christoph Keplinger, Jeong-Yun Sun, and Science/AAAS. Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.