Abstract
With the rapid development in biomedicine, biochemistry and nanotechnology, there are increasing demand for manipulation of micro scale objects. Precise separation and flexible manipulation of micro-sized particles and cells are essential for many biochemical processes in cell biology, drug delivery, analytical chemistry, disease diagnosis and cancer treatment. In order to precisely manipulate micro-sized particles and cells, a range of microfluidic techniques have been well developed, such as optical tweezer, magnetophoresis, acoustophoresis, dielectrophoresis, deterministic lateral displacement and inertial microfluidics. Acoustofluidics based micro-sized particles and cells manipulation has gained increasing prominence recently because of its excellent biocompatibility and low energy consumption. As a result, acoustophoresis based microfluidic techniques have been widely applied in disease detection and various biochemical analyses such as separation, patterning, trapping and cell focusing. Further, it has an enormous potential to be developed into portable devices with broad application prospects in the market. In the studies presented in this thesis, surface acoustic wave-based microfluidics devices are used to (1, 2) sort microparticles, droplets and cells based on fluorescence labelled biomarkers, (3) separate microparticles based on their size and mechanical properties and (4) sort hydrogel droplets and cells based on their electrical impedance and deformability.