Dielectrowetting driven spreading of liquid crystal droplets

Microfluidics is the science that processes or manipulates small amounts of fluids. In microfluidics, control of the wetting properties of surfaces is extremely important in both scientific research and industrial applications. The wetting of solid surfaces can be modified by altering the surface free energy balance among the solid, liquid and vapor phases. This thesis deals with the experimental investigation of liquid crystals using dielectrowetting, a novel technique based on liquid dielectrophoresis. Liquid crystal droplets are deposited on an engineered surface provided with interdigitated electrodes with micrometric features fabricated using standard photolithography. On electrode surfaces, two types of functionalization are performed: a lubricant-infused surface and a solid fluoroplastic coating. The influence of the applied nonuniform electric fields on the spreading of liquid crystal droplets on the two types of functionalized surfaces is investigated by means of high-resolution video cameras. The resulting behavior of liquid crystal droplets is obtained by processing the acquired images offline with custom-made programs.