text: The coffee ring effect is utilized in convective deposition by researchers wanting to order particles on a substrate using capillary-driven assembly, replacing a stationary droplet with an advancing meniscus drawn across the substrate.  This process differs from dip-coating in that evaporation drives flow along the substrate as opposed to gravity.
  Convective deposition can control particle orientation, resulting in the formation of crystalline monolayer films from nonspherical particles such as hemispherical, dimer, and dumbbell shaped particles. Orientation is afforded by the system trying to reach a state of maximum packing of the particles in the thin meniscus layer over which evaporation occurs. They showed that tuning the volume fraction of particles in solution will control the specific location along the varying meniscus thickness at which assembly occurs. Particles will align with their long axis in- or out-of-plane depending on whether or not their longer dimension of the particle was equal to the thickness of the wetting layer at the meniscus location. Such thickness transitions were established with spherical particles as well. It was later shown that convective assembly could control particle orientation in assembling multi-layers, resulting in long-range 3D colloidal crystals from dumbbell shaped particles. These finds were attractive for the self-assembled of colloidal crystal films for applications such as photonics. Recent advances have increased the application of coffee-ring assembly from colloidal particles to organized patterns of inorganic crystals.