Development of a non-continuous micro-flow opto-wetting droplet manipulation technology

The aim of this research is to develop a light actuated droplet manipulation system. This research utilized ultraviolet to activate oxidation-reduction mechanism of nano-TiO₂ photocatalyst coating on the base material. The water-affinity of the base material changed due to the decrease in free-energy of the material surface. The contact angle between the liquid droplet and base material also changed to facilitate the manipulation purpose. In this study, the system that was developed includes which ultraviolet masking device, moving platform, main frame structure etc. The software was developed by using Microsoft Visual Basic 6.0. Upon completion of hardware and software integration, experiments were carried out to verify system functionalities. This study developed a non-continuous opto-wetting droplet manipulation technique. By exposure to 6.8 mW UV light, the surface tension of coating nano-TiO₂ (Anatase type , 3.5%, PH 1.5 , and with average diameter of 69 nm) changed for the sake of changing hydrophilic. The change in surface tension is applied to drag the droplet. The moving rate of dragging was 3.33 mm/sec. This technique overcomes the shortcoming of opto-electrowetting technique. The programming function of this technique can also be applied to the clinic test in the future.