EXTREME WATER CONFINEMENT AMIDST SUPERHYDROPHILIC SU8 MICROPATTERNED WALLS

Control of motion of drops on solid surfaces and their mechanism is relevant in many nanotechnology processes and water vapour harvesting practices. Biomimetic strategies comprise designing topographic and chemical heterogeneities on solid surfaces, which can pin and steer drops towards required specific locations. Herein, a simple approach to realize ‘‘confined smart'' liquid drops on surfaces with hydrophilic regions surrounded by superhydrophilic boundaries upon applying a CF4/Ar plasma to a microstructured silicon substrate is presented. The key property of confinement was controlled topographically under simple selective patterning of SU-8 and chemically by plasma modification. Surface chemical and morphological modification of plasma on the SU-8 patterned silicon surfaces were evaluated. Moreover behaviour at the underwater solid/ liquid interface and in underwater oil wettability were investigated. According to this approach, the proposed platform is suitable for biological and chemical applications, for capturing drops for Lab-on-a-chip devices or water harvesting applications.