Wrinkles as Shape-Tunable Boundaries

Abstract

Recently, spontaneously formed wrinkles on hard coating-capped elastomer surfaces have attracted the attention of both the scientific and applied research communities, because of their simple fabrication process and practical potential in diverse applications as a shape-tunable boundary. The depth and stripe orientation of the wrinkle can be controlled by applying compressive strain. Our group has focused on tuning the structure of wrinkles by exerting additional strain. This is almost impossible for micropatterns fabricated on a hard, e.g., Si wafer; therefore, our technique is based on a soft substrate and the non-linear response of the system to external strain. The dynamic shape-tunability of the micropatterns shows potential for new applications, in which switching states of a system could be induced by a change in the physical boundary conditions, namely, the shape of wrinkles. This article summarizes our recent work on shape-tunability of wrinkles and the application of shape-tunable wrinkles to tunable optical diffusion, liquid manipulation, liquid crystal alignment, and tunable friction. Our research demonstrates that shape-tunable wrinkles provide new physical boundary conditions that can control the states of the bounded material and of phenomena that occurs at/through the interface. We expect that many other systems that interact with the tunable boundary will lead to the discovery of new phenomena and technologies.