Peeling stickers are key to stretchable electronics
Cambridge, Mass - A study of stickers peeling from windows could lead to a new way to control the fabrication of stretchable electronics, according to a team of researchers.
Stretchable electronics would allow electronic devices to be embedded into clothing, surgical gloves, electronic paper or other flexible materials, but have been difficult to engineer because the electrical wiring tends to be damaged as the material twists.
The team initially launched the project as an analysis of the wrinkling and delamination of stickers, such as the small blisters that appear in stickers attached to car windows.
"It's something that's around you all the time — but if you look at it a different way you can see something new," says Pedro Reis, applied math instructor at MIT and senior author of the paper.
Delamination occurs due to different rates of heat-induced expansion between a thin film and the surface to which it is attached, or through compression of the surface.
The researchers stretched and compressed surfaces with thin films attached to them, and measured the resulting blisters. They found that blister size depends on the elasticity of the film and the substrate and the strength of adhesion between them.
They then realized that by intentionally creating delaminated surfaces, they could design devices that allow wires attached to a surface to move with the material without breaking. If the wires are already partially separated from the material, they won't break under stress.
Stretchable electronics have already been used in applications such as electronic paper and flexible displays. Prototype phones are also in the works. The new study suggests that ultra-thin, flexible but strong materials such as graphene are ideal candidates for such applications.
The study is published in the online edition of the Proceedings of the National Academy of Sciences.