Laser-Induced Spallation of Microsphere Monolayers

TL;DR

This study investigates the adhesion and detachment mechanisms of polystyrene microsphere monolayers on aluminum-coated substrates using laser-induced spallation, combining optical interferometry and microscopy to analyze adhesion forces and morphology.

Contribution

It introduces a combined optical and mechanical approach to measure microsphere adhesion forces and reveals a novel delamination morphology of partially detached monolayer flakes.

Findings

Estimated microsphere adhesion force from substrate displacement measurements.

Reasonable agreement between adhesion estimates from different experimental methods.

Identification of a unique partially detached monolayer flake morphology.

Abstract

The detachment of a semi-ordered monolayer of polystyrene microspheres adhered to an aluminum-coated glass substrate is studied using a laser-induced spallation technique. The microsphere-substrate adhesion force is estimated from substrate surface displacement measurements obtained using optical interferometry, and a rigid-body model that accounts for the inertia of the microspheres. The estimated adhesion force is compared with estimates obtained from interferometric measurement of the out-of-plane microsphere contact resonance. Reasonable agreement is found between the two experiments. Scanning electron microscope images of detached monolayer regions reveal a unique morphology, namely, partially detached monolayer flakes composed of single hexagonal close packed crystalline domains. This work contributes to an improved understanding of microsphere adhesion and demonstrates a unique monolayer delamination morphology.