Researchers from Ecole Polytechnique Fédérale de Lausanne (EPFL) in France have created a new kind of stretchable electronic that quadruples in length. The newly developed technology could be used to propel the areas of artificial skin, connected clothes and skin-like sensors.
The electronics are based on conductive tracks, which are typically hard-printed on a board, but in this case are almost as flexible as rubber and can be stretched in all directions. The conductive tracks allow someone to stretch the material a million times without it cracking or even interrupting conductivity.
This new metallic and partially liquid film could potentially be used to make circuits that can be twisted and stretched, which could then be used for artificial skin in work with prostheses. In addition, since the sensors can form to the body and allow a wide range of movement, they could also be used in monitoring for biological and medical applications. “We can come up with all sorts of uses, in forms that are complex, moving or that change over time,” said Hadrien Michaud, a PhD student at the Laboratory for Soft Bioelectronic Interfaces (LSBI) and one of the study authors.
Many research teams have been working on elastic electronic circuits, which can be difficult since usually circuit components are rigid. One way to overcome this challenge is by applying a liquid metal to a thin film in polymer with elastic properties. Up until this point, working with liquid metals has resulted in very thick structures. But now, the EPFL team has been able to create very narrow tracks, several hundredths of a nanometer thick, using deposition and structuring methods.
What also made the new stretchable electronics possible was the ingredients that the researchers used. They opted to use gold and gallium. Gallium possesses a low melting point and good electrical properties.“So it melts in your hand, and, thanks to the process known as supercooling, it remains liquid at room temperature, even lower,” said Arthur Hirsch, a PhD student at LSBI and co-author of the study.
The layer of gold ensures the gallium doesn’t separate into droplets once it comes in contact with the polymer, in effect, keeping it conductive.