LAUSR

The dynamic and static properties of structured surfaces have important functions in nature. In particular, wrinkles have important static roles, for example, increasing surface area, but the dynamic roles of wrinkles remain poorly understood. Specifically, to understand and utilize the dynamic functions of wrinkles, it is necessary to observe wrinkle formation directly. In this study, a polyion complex (PIC) was formed on a hydrogel surface by electrophoresis, and the process of wrinkle formation through a transparent electrode was directly observed. By quantitative analysis of the wavelength and amplitude of wrinkles, we found that the wrinkles moved randomly in a wavy pattern during their growing process in the initial stage. Furthermore, the direction of wavy motion of wrinkles was controlled by the compression of hydrogels in the in-plane direction. The present study provides important insights into the fabrication of wrinkled surfaces with a controlled flow direction; opening the possibility for active wrinkles used in the development of functional surface structures as actuators that are capable of transporting small objects in water. This article is protected by copyright. All rights reserved.