Compressive Behaviors of Micropillar Patterns Made of PDMS Material using the Finite Element Method

Abstract

Hydrophobic surface is a surface having the ability of water repellent which is frequently coated on medical devices and marine structures. This hydrophobic surface can fabricate from micro-pattern sheets consisting of groups of micropillars arranged into unique micro-patterns which are normally made of low surface energy materials. Thai Microelectronics Center (TMEC) has fabricated micropillar sheets from PDMS for various micropillar array patterns from soft lithography techniques. However, these micropillar sheets were relatively weak under pushing forces. This research aimed to understand compressive behaviors of rectangular prism micropillars having different aspect ratios (ratio of width to length of a rectangular cross-section) and micro-patterns consisting of micropillars having rectangular cross-section and square cross-section by using ANSYS Mechanical APDL program. We found that the aspect ratio of prism micropillars had not influents on both elastic stiffness and compressive strength under compressive loading. The lateral collapse of micropillars were observed on all micro-patterns during compressive loading. Furthermore, the sharklet micro-pattern had the highest compressive strength with maximum compressive pressure of 9.87 kPa. Finally, as loading contact area of micro- patterns increases, the compressive strength increases while the water contact angle decreases.