Date of Award

Summer 2022

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Dr. Daewon Kim

Committee Co-Chair

Dr. Foram Madiyar

First Committee Member

Dr. Mandar Kulkarni

Abstract

This work aims to develop an advanced and cost-effective fabrication process to produce a simplified gecko-inspired microstructure with two-photon polymerization and polymer molding, aimed to improve the adhesive properties of microstructures. Such adhesive microstructures can be implemented for multi-purpose adhesive grasping devices, which have recently gained significant interest in the space exploration sector. Previous gecko-inspired microstructures were reviewed, and the new gecko-inspired microstructures have been developed with the adaptation of additive manufacturing methods for facile fabrication. The examined microstructures in this thesis were the tilted mushroom-shaped and wedge-shaped designs, which could both maximize adhesion by shearing the micropillars toward the tilted direction when preload force is applied. The improved microstructure fabrication process could produce micropillars in the height of 270 μm with soft polymer without defects. However, the miniaturized micropillars in the height of 40 μm, frabricated with the same process, had broken tips and missing structures. The effects of the scale, height, and shape of the micropillars in controllable dry adhesion were investigated through the experiments. The adhesion of the microstructures with artificial gecko setae in the height of 270 μm was 2 times higher than the microstructures with 40 μm of height. Meanwhile, the microstructures that consisted of long and short artificial gecko setae had inferior adhesive performance to the microstructures having uniform long setae on all tested surfaces. Meanwhile, the result showed no direct correlation between the surface roughness of the attached surface and the adhesive performance of the microstructures. The wedge-shaped design was determined to have higher adhesion than the tilted mushroom-shaped design due to lower structural resistance on bending and higher effective contact area.

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