Manipulation Of Single/Multiple Phase Flow On Microchips And Its Application

Microfluidics, the core technology of the miniaturized total analysis systems (μ-TAS), is the science and technology of systems that process or manipulate small amounts of fluids (nanoliter to femtoliter) in micro/nanostructure. With the development of microfluidics, researchers are able to perform operations in traditional laboratories such as sampling, dilution, reation, seperation and dection on a microchip. In the past decade, microfluidics have been applied in biochemical analysis, cell biology, disease diagnosis, fuel cell development and multifunctional micro/nanomaterial synthesis. The present work intends to manipulate single phase and multiphase flow on developed microchips, and to study possible applications of fluid control in chemical and biochemical analysis.In chapter 1, recent progress of manipulating single phase and multiphase flow in microchannel are reviewed, including a brief introduction to the formation theory of laminor flow and droplet flow, their characteristics and their applications in biochemical analysis, cell biology, disease diagnosis, fuel cell and multifunctional micro/nanomaterial synthesis.In chapter 2, a microfluidic system for Drosophila embryo’s online development and observation is presented. The system is capable of developing the embryo’s anterior and posterior halves controlled at different temperature environments, and it can be easily coupled with a confocal microscopy for real-time image acquisition. With the assembled microfluidic platform, thermal gradients of 25℃/16℃, 25℃/18℃,25℃/20℃ were applied across live Drosophila embryos, which resulted in changing the relative development rate of the two halves of the embryos. It was found that the developing difference was also related to the direction of thermal gradients. These observations help to better understand the compensatory mechanism of the Drosophila embryo’s development under environmental perturbations.In chapter 3, a facile approach for wettability-patterning of the micro channels of glass chips was developed. The architecture of soda-lime glass/quartz glass hybrid chip was designed to facilitate effective OTS-SAM degradation by deep UV-light. The established approach, together with side-by-side laminar-flow patterning technique, was applied to prepare various finely patterned channel networks for different tasks of flow profile switching. Smooth flow profile switching either from W/O droplets to O/W droplets or from W/O (or O/W) droplets to separated continuous flows of two phases, or vice versa, can be realized on the micro glass chips prepared with the developed wettability-patterning approach. In addition, with the wettability patterned channel networks, W/O/W double emulsions were successfully created. The prepared double emulsions were monodisperse and had narrow size distribution with coefficient of variation values less than 8%. Moreover, both the size and the number of the inner droplets could be controlled by adjusting the flow rates.In chapter 4, the flow profile switching from W/O droplets to laminar flow achieved in chapter 3 was applied to perform on-chip fast liquid/liquid extraction in combination with off-chip liquid chromatography (LC) analysis for the determination of partition coefficient of pharmaceuticals. The results demonstrated that this method was valid and fast with low reagent consumption.In chapter 5, the present work is summarized and future work is sugguested for this research area.