Stretchable, Transparent, Ionic Conductors
In a paper published in Science, we describe a class of devices fabricated using stretchable, transparent, ionic conductors.  This work represents the first demonstration that electrical charges carried by ions, rather than electrons, can be put to meaningful use in fast-moving, high-voltage devices. These devices are highly deformable and fully transparent.  They can operate at frequencies beyond 10 kHz and under voltages above 10 kV. We demonstrate transparent actuators that produce rapid and powerful movements in response to electrical stimulation.  We also demonstrate a transparent loudspeaker capable of producing sound across the entire audible range. See online discussion about this work. 

A membrane of transparent, insulating rubber (dielectric elastomer) is sandwiched between two layers of transparent, conductive gel (hydrogel). 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. The materials expand in area under electricity.

YouTube Video

A gel-based audio speaker demonstrates the capabilities of stretchable ionic conductors, long thought limited in application. 
(Footage courtesy of Science/AAAS.)


Related.

Stretchy, see-through material conducts electricity | Science News

Bio-inspired speaker uses clear gel to play music | NewScientist

This "Ionic" Speaker Is Stretchable, See-Through and Mind-Blowing | gizmodo

Transparent, flexible speaker runs on ions | Nbcnews

Stretchable Ionics | imechanica Journal Club Theme of Sept 2013

Other online reports. 

Citation Info.

Christoph Keplinger, Jeong-Yun Sun, Choon Chiang Foo, Philipp Rothemund, George M. Whitesides, Zhigang Suo. Stretchable, transparent, ionic conductors. Science 341, 984-987 (2013).