  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.
