Figure 4: (a) Superposition of 100 frames from a video sequence showing the motion of seeding particles near the hot spot. Note that the motion along the interface is directed towards the hot spot. Reproduced with permission from [70]. (b) Superposition of successive frames illustrating drop switching by local thermocapillary actuation. The arrow indicates the laser location observed by the fluorescence of the water-dye solution. Reproduced with permission from [53].