Wettability control and flow regulation using a nanostructure-embedded surface.

This work addresses the synthesis, integration and characterization of a nanostructure-embedded thermoresponsive surface for flow regulation. In order to create a hierarchic structure which consists of microscale texture and nanoscale sub-texture, hybrid multilayers consisting of poly(allylamine hydrochloride) (PAH), poly(acrylic acid) (PAA) and colloidal silica nanoparticles (average diameter = 22 nm and 7 nm) were used. Based on the electrostatic interactions between the polyelectrolytes and nanoparticles, a layer-by-layer deposition technique in combination with photolithography was employed to obtain a localized, conformally-coated patch in a microchannel.

Impact of drops on the surface of immiscible liquids.

Impact of drops on the surface of an immiscible liquid is studied. We show that in addition to the commonly-observed lens structure at the air-liquid interface, drops released from critical heights above the target liquid can sustain the impact and at the end maintain a spherical ball-shape configuration above the surface despite undergoing large deformation. The existence of this metastable state of the drop above the free surface and its transition into the more stable submerged lens configuration at the air-liquid interface is investigated.