Thermocapillary flow over superhydrophobic surfaces

We present an experimental realization of thermocapillary flow over a superhydrophobic surfaces subjected to controlled spatial temperature gradients. We demonstrate how a superhydrophobic surface can provide an interface for Marangoni stresses to drive fluid flow, thus allowing for thermocapillarity to be applied to closed fluidic systems lacking a continuous fluid-liquid interface. We show that hierarchical superhydrophobic structures are necessary in order to prevent the Cassie to Wenzel transition, enabling stable flows over long durations of time. Finally, using a Hele-Shaw chamber containing such superhydrophobic surface, we demonstrate the use of localized heating for obtaining desired flow patterns.