Morphological analysis of crease patterns formed on surface‐attached hydrogel with a gradient in thickness

ABSTRACT The morphology of crease pattern formed on the surface‐attached hydrogel with a gradient in thickness is analyzed. We label the hydrogel surface at the creased state with fluorescent polyelectrolyte, which enables us to visualize surface morphology of creases using the fluorescent microscopy. Various morphological features of crease patterns are analyzed at different thickness of hydrogel, or characteristic spacing of creases λc,max, to examine the self‐similarity of crease morphology at different length scales. Some morphological features show no λc,max dependence, implying the self‐similarity, while others show weak λc,max dependence with positive values of the exponent of power law fit for the plots. We infer that such nonself‐similarity is originated from the variations in the kinetics of swelling and creasing of hydrogel, the effect of surface tension, or the reduction in t…