Recent Developments on Colloidal Deposits Obtained by Evaporation of Sessile Droplets on a Solid Surface

TL;DR

This review paper discusses recent advances in understanding how various parameters influence the formation of colloidal deposits from evaporating droplets on solid surfaces, highlighting complex transport phenomena and potential applications.

Contribution

It provides a comprehensive overview of recent research on deposit patterns, parameters affecting them, and the physics underlying colloidal evaporation on solid surfaces.

Findings

Marangoni effects significantly influence deposit patterns.

Particle size and shape affect the deposit morphology.

Studies demonstrate particle sorting in bi-dispersed suspensions.

Abstract

Understanding flow patterns and coupled transport phenomena during evaporation of droplets loaded with colloidal particles is central to design technical applications such as organizing proteins/DNA on a solid surface. We review recent reports on evaporating sessile droplets of colloidal suspensions on a solid surface. Starting from the classical mechanism of formation of a ring-like deposit, we discuss the influence of several problem parameters. Notably, thermal or solutal Marangoni effect, particle size, particle concentration, particle shape, substrate wettability, pH of the suspension etc have been found important in controlling the deposition pattern. The deposit pattern complexity and shape have been attributed to the underlying coupled transport phenomena during the evaporation. We discuss important regimes maps reported for different types of deposit, which allow us to classify the deposits and coupled physics. We also present studies that have demonstrated particles sorting in an evaporating bi-dispersed colloidal suspensions on a solid surface. Finally, some remarks for the future research opportunities in this arena are presented.