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

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 regime maps reported for
different types of deposits, which allow us to classify the deposits and
coupled physics. We also present studies that have demonstrated particles
sorting in an evaporating bidispersed colloidal suspension on a
solid surface. Finally, some remarks for the future research opportunities
in this arena are presented.