Window Stickers Lead To Stretchy Electronics

Engineers would love to embed flexible electronics into things like paper, or surgical gloves or conventional clothing. But the wiring usually gets twisted and damaged. Now MIT researchers have found inspiration in an unlikely place—the annoying air pockets that pop up in parking pass stickers on car windows.

Those bubbles arise because the thin sticker film expands at a different rate than the window glass when they both heat up. And the opposite is also true—the material can compress differently than the glass until it separates and blisters form.

The scientists were studying this kind of wrinkling behavior. They developed a model that predicted the formation, size and evolution of the bubbles that depends on three things: the elasticity of the film and the glass, and the strength of the bond between them.

Then they realized that carefully controlled delamination could be applied to make elastic electronics. Wires in the bubbly elastic material would start out only partially attached to a surface. So there’d be some slack allowing for safe stretching and twisting. The work appears in the Proceedings of the National Academy of Sciences, and shows that a different approach can make a tough problem less sticky.

—Cynthia Graber