Smectic bubbles in strong external electric fields

Smectic bubbles as fluid structures with a huge surface-to-volume ratio represent unique examples of quasi-two-dimensional (2D) fluids. We investigate the behavior of islands, local regions with larger film thickness, in the presence of strong inhomogeneous electric fields. The islands, which can be considered here as 2D analogs of liquid droplets, become charged and are repelled by a needle-shaped electrode in contact with the film. The mechanism has strong similarities to electrospraying and electrospinning, but because of the constraint of the thin film, the motion is confined to the film plane. Interestingly, the phenomenon depends on the polarity of the electric field. This indicates that the charging of the islands is related to the asymmetric ion mobilities in the film material. To prevent sedimentation of the islands, the experiments were performed under microgravity conditions on parabolic flights.