Surface acoustic wave for microfluidic applications

Surface acoustic wave-based (SAW) microfluidics attracts attention from microfluidic research community due to its simple fabrication, large force and fast, yet efficient operation.The scope of this project is to develope a microfluidic platform based on the advantages offered by surface acoustic wave.Firstly, a literature review is given to present the state of the art of the emerging field of SAW-based microfluidics.SAW-based microfluidics can be categorized into droplet-based applications and continuous-flow applications.Droplet is actuated into unique behaviours depending on the applied SAW power.A wide range of droplet based applications have been employed utilizing these behaviours.In a continuous-flow system, applications are further categorized based on the interference of travelling SAW and standing SAW with the bulk liquid.The fabrication of SAWmicrofluidic platform is based on standard microfabrication technology.Electrodes are patterned and lift off on a piezoelectric substrate to form a SAW device.Employing soft lithography, microfluidic channel system is fabricated and bonded to the SAW substrate.First, the utilization of active surface-acoustic-wave-driven micromixers was investigated.Due to the small channel dimensions, flow characteristics in microfluidic devices was naturally laminar and mixing at microscale is poor.Large disturbance force induced h by transverse SAW could be exploited to enhance mixing quality effectively and with high throughput.Surface wave with a frequency of megahertzs was launched perpendicular to a side-by-side flow of water and fluorescent dye solution.Mixing quality was significantly enhanced compared to diffusive mixing.In this type of SAW mixer, two different designs of electrododes for generating SAW were studied : parallel design and focusing design.Nguyen Nam-Trung for his invaluable guidance and encouragement during my research project at the Thermal and Fluid Research lab.His insight knowledge