Self-propelled sweeping removal of dropwise condensate

Qu, X., Boreyko, J. B., Liu, F., Agapov, R. L., Lavrik, N. V., Retterer, S. T., Feng, J. J., Collier, C. P. & Chen, C.-H.

Appl. Phys. Lett. 106, 221601 (2015)

Abstract - Dropwise condensation can be enhanced by superhydrophobic surfaces on which the condensate drops spontaneously jump upon coalescence. However, the self-propelled jumping in prior reports is mostly perpendicular to the substrate. Here, we propose a substrate design with regularly spaced micropillars. Coalescence on the sidewalls of the micropillars leads to self-propelled jumping in a direction nearly orthogonal to the pillars and therefore parallel to the substrate. This in-plane motion in turn produces sweeping removal of multiple neighboring drops. The spontaneous sweeping mechanism may greatly enhance dropwise condensation in a self-sustained manner.