Capillary-Induced Clustering of Thermoresponsive Micropillars.

In this study, we demonstrate the controllable clustering of thermoresponsive high-aspect-ratio hydrogel pillars by modulating the elastic modulus of the materials. Generally, high-aspect-ratio polymeric pillars readily cluster owing to the effect of capillary force and adhesion. However, this unstable behavior hinders the implementation of various functionalities such as wetting, adhesion, and energy harvesting on surfaces with such pillars.