Three-dimensional microplate formation with evaporating nanoparticle suspensions on superhydrophobic surfaces

The concept of evaporation driven self-assembly of nanoparticles is exploited to fabricate three dimensional microstructures on textured superhydrophobic surfaces. The evaporative droplets always remain in Cassie-Baxter state during the process of drying. However, the wetting transition from Cassie to Wenzel state has been observed for pure water drop on similar surfaces. After complete evaporation, residual particles form a (micro-) plate like structure. The area of the final structure is smaller than the initial contact area of the drop. Evaporating droplets are visualized from two directions to keep track of the drop radius and apparent contact angle.