Jetting micron-scale droplets onto chemically heterogeneous surfaces

We report experiments investigating the behavior of micron-scale fluid droplets jetted onto surfaces patterned with lyophobic and lyophilic stripes. The final droplet shape is shown to depend on the droplet size relative to that of the stripes. In particular, when the droplet radius is of the same order as the stripe width, the final shape is determined by the dynamic evolution of the drop and shows a sensitive dependence on the initial droplet position and velocity. Lattice Boltzmann numerical solutions of the dynamical equations of motion of the drop provide a close quantitative match to the experimental results. This proves helpful in interpreting the data and allows for accurate prediction of fluid droplet behavior for a wide range of surfaces.