Transparent speaker made from artificial muscle

Jeong- Yun Sun and Christoph Keplinger have found an ion conductive material stretchable, transparent and biocompatible. It is made up of gel and rubber. This speaker is completely made of a transparent thin film of rubber sandwiched between two layers of gel, consisting, inter alia, saltwater and the latter act as electrodes. When the gel layers are traversed by an electric signal, the rubber disc shrinks and expands successively, and very quickly. This vibratory movement then emits high frequency sounds in the same way as would a speaker can do. This transparent model can reproduce all the sounds in the audible range of human hearing, i.e. 20 Hz to 20 kHz, as shown in this video. They are not yet to come into your living room next to equip a stereo. Jeong- Yun Sun and colleagues at SEAS (Harvard School of Engineering and Applied Sciences) built this prototype primarily as a technology demonstrator. Their goal is to show that it is possible to transit electric charges and therefore produce a stream of pulses by using not by electrons as usual, but the ions. This experience of Harvard University, Massachusetts is a major step in the development of the technology of ionic conduction. Indeed, researchers have managed the feat twice to develop a device that not only withstand high voltages, but also is able to change its structure very quickly.

The ions are much heavier than electrons and bulky chemical species, and therefore they move more slowly. Compared to conventional electrical conductors, ion conductors have several advantages. First, they can stretch to several times their length without changing their resistivity. Then their transparency opens the door for many optical applications. Finally, they are biocompatible, making them prime candidates for the implementation of artificial skin or muscles. Among other applications, the researchers believe such a high transparent speaker glued directly on a TV screen, Smartphone or tablet, and directly emit sound from the entire surface of the device. Such a device attached to the windows of an apartment could be used to actively cancel sound from outside. But researchers are also thinking of glasses able to adapt their length or even the “soft machines."