Sorting of droplets by migration on structured surfaces

• Wilfried Konrad and
• Anita Roth-Nebelsick

Beilstein J. Nanotechnol. 2011, 2, 215–221, doi:10.3762/bjnano.2.25

• achieved. For example, different chemical reactants can be directed to different “assembly” lines. Also the speed of the droplets can be controlled. Surfaces similar to our patterns are not uncommon in nature. Insects show a wide variety of ornamentations of their cuticle, their compound eyes and wings [10

Superhydrophobic surfaces of the water bug Notonecta glauca: a model for friction reduction and air retention

• Petra Ditsche-Kuru,
• Erik S. Schneider,
• Jan-Erik Melskotte,
• Martin Brede,
• Alfred Leder and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 137–144, doi:10.3762/bjnano.2.17

• (Figure 2D) and reach a density of approximately 5.8 × 106 mm−2. The underside of the elytra is only able to hold a very small volume of air due to their minor height. The little air film, however, might primarily help to keep the wings dry. The upper side of the elytra is hierarchically structured by

• wings dry and save air for respiration, but friction reduction might also be an additional advantage for the backswimmer while hunting. An overview of the structural parameters of the investigated surfaces is given in Table 1. All investigated surfaces are more or less superhydrophobic (Table 2

• surface. Also the decreased air–water interface itself leads to a higher resistance against water pressure according to the model of Crisp and Thorpe [17]. The tiny, but stable, air film on the underside of the elytra seems to be more relevant to keep the wings dry rather than playing a role in the