Generalizing Co-operative Evaporation in Two-Dimensional Droplet Arrays

TL;DR

This paper develops a generalized theoretical limit for the lifetime of two-dimensional droplet arrays during evaporation, revealing insensitivity to geometrical details and introducing a novel method for patterning particles via symmetry breaking.

Contribution

It introduces a simple theoretical model for droplet array evaporation and uncovers a new topologically-driven symmetry breaking mechanism for particle patterning.

Findings

Theoretical limit for droplet array lifetime is independent of detailed geometry.

Evaporation characteristics are robust across various droplet-substrate configurations.

A new pathway for particle patterning using symmetry breaking in evaporating droplet arrays.

Abstract

Sessile droplets exposed to an incipient condition lead to an inevitable loss of mass, which is critical in many practical applications. By considering an arbitrarily configured two-dimensional array of droplets, here we provide a simple generalized theoretical limit to their lifetime in an evaporating state. Notwithstanding the geometrical and physical complexity of the effective confinement generated due to their cooperative interactions, we show that the consequent evaporation characteristics may be remarkably insensitive to the topographical details of the overall droplet organization, for a wide range of droplet-substrate combinations. With subsequent deployment of particle-laden droplets, however, our results lead to the discovery of a unique pathway towards tailoring the internal flows within the collective system by harnessing an exclusive topologically-driven symmetry breaking phenomenon, yielding a new strategy of patterning particulate matters around the droplet array.