Adhesion of Biologically Inspired Vertical and Angled Polymer\nMicrofiber Arrays

Abstract

This paper proposes an approximate adhesion model for fibrillar adhesives for developing a fibrillar adhesive design\nmethodology and compares numerical simulation adhesion results with macroscale adhesion data from polymer\nmicrofiber array experiments. A technique for fabricating microfibers with a controlled angle is described for the first\ntime. Polyurethane microfibers with different hardnesses, angles, and aspect ratios are fabricated using optical lithography\nand polymer micromolding techniques and tested with a custom tensile adhesion measurement setup. Macroscale\nadhesion and overall work of adhesion of the microfiber arrays are measured and compared with the models to observe\nthe effect of fiber geometry and preload. The adhesion strength and work of adhesion behavior of short and long vertical\nand long angled fiber arrays have similar trends with the numerical simulations. A scheme is also proposed to aid\nin optimized fiber adhesive design.