Abstract
The purpose of this dissertation is to develop and analyze a biomimic texture-induced superhydrophobic (SHP) surface as well as applied to the manipulation of electro-induced microfluidic systems. In this study, a novel fabrication of self-forming high-aspect-ratio polymer nanopillars under reactive ion etching (RIE) process was proposed in which the fabrication process need neither nano-lithography definition nor catalyst pre-forming during inorganic growing and showed a highly integration flexibility of other N/MEMS fabrication processes. Based on lotus leaf biomimic, a SHP surface with multi-length scale was successfully constructed and the contact angle (CA) can be larger than 155o and the contact angle hysteresis (CAH) can be less than 10o which was similar to the properties of real lotus leaf. In the application aspect, it is more important of the phenomena description and theoretical study of the dynamic process on such a hierarchical SHP surface. Due to the limitation of the preparation of hierarchical SHP surface, however, the study of droplet dynamic impinging to the surface was still insufficient. As a result, the free fall droplet impinging test onto SHP surface was observed and analyzed in droplet deformation and time-varied CA so as to categorized the three wetting schemes: non-wetting, micro-wetting, and nano-wetting and the textured-induced energy barriers were estimated. In order to improve the SHP stability, Parylene-C coating and Teflon spray coating were utilized to increase the rigidity and intrinsic CA of polymer nanopillars. The result shows a better SHP surface with higher CA (~165o) and lower CAH (<3o). For further application, the biomimic SHP surface was integrated with electro-induced microfluidic manipulation system and demonstrated a reversible actuation of in-situ droplet deformation and lateral moving on nanopillars SHP surface. The contact angle decrease can up to 50o under voltage applied of 150 Vac.