When a colloidal drop evaporates on an inclined surface

Colloidal drops including micro- and nanoparticles usually leave ring-like deposit patterns when they evaporate on a flat surface, as well known as the coffee-ring effect. A curious and important geometry is an inclined surface, where colloidal drops may evaporate in different ways with a flat surface. Prediction of final deposit patterns on an inclined surface is inaccessible due to complexity of evaporation processes and profound competition of hydrodynamic and gravitational effects. Here we explore how gravitational force affects evaporation dynamics and final deposit patterns of colloidal drops by varying particle size, particle concentration, and tilting angle. We show and explain how inclination changes evaporation rates and final patterns. This study would shed light on new knowledge for manipulation of external forces on final deposit patterns of colloidal fluids under various situations.