Control of droplet evaporation on smooth chemical patterns

We investigate droplets evaporating on flat pinning-free substrates with smooth wettability patterns. Symmetric patterns lead to a hierarchy of bifurcations in the three-dimensional parameter space represented by droplet cross sectional area $A$, midpoint $\ensuremath{\ell}$, and footprint $R$. In asymmetrical patterns, presence disconnected stable branches forces move towards one direction, hence showing that droplet's motion can be controlled upon evaporation.