Wrinkling, blisters and delamination on stickers applied to curved or bendable surfaces are usually an annoyance: however, a team of researchers — including one at MIT — recently examined these phenomena and found a new, powerful approach to fabricating stretchable electronics that could pave the way to the production of components with very high mechanical resistance.
Blisters are usually generated by a non-uniform exposure to heat, which causes an uneven rate of expansion between a thin film and the surface to which it is attached. Common examples of this phenomenon include blisters formed in stickers attached to a window after prolonged exposure to sunlight, or those formed after the underlying surface is twisted.
Delamination is seen as a side effect to be prevented and avoided in most applications, as it can drastically reduce adherence to the surface and degrade the mechanical properties of the film. While trying to study the dynamics of how blisters appear on stickers, however, a team of researchers accidentally found out that it could be applied to electronics to allow for components with strongly improved mechanical properties.
If the wires are already partially separated from the material, researchers found, they will be much less prone to breaking under repeated mechanical stress, including stretching, twisting and bending.
Other researchers have previously tackled the issue of mechanically resistant electronics, with some degree of success. For instance, U.S. researchers have found a promising solution that involves an innovative structure at nanoscale level offering a 140% improvement in terms of resistance to twisting.
This new approach appears all the more promising because the researchers have also managed to formulate and verify a model to describe how blistering works, which scientists and engineers can use to predict the size of the blisters that will form under specific conditions, and control it by changing the elastic properties of the film and wires. The study also suggested that ultra-thin, flexible but strong materials such as graphene are ideal candidates for stretchable electronic applications.
Research in this field, along with that on plastic electronics, could bring to circuitry embedded in all sorts of items, from surgical gloves to electronic paper and even stretchable mobile phones, even though these results still look very far from being achievable — let alone mass-produced — at this point.
The study was published in the online edition of the Proceedings of the National Academy of Sciences this month.