Micro Particle Image Velocimetry Measurement Of Electroosmotic Flow In Micro Channels

Micro-size mechanical devices are becoming more crucial both for industry and academic research. The integrated circuit (IC) technology, which has been developed and commercialized successfully, give an approach to the realization of people's original imagination about micro-machined devices. From that time, concepts like Micro Electro Mechanical System (MEMS), Micro Total Analysis System (μ-TAS), or Lab on a Chip have been extensively mentioned. On the basis of these rough ideas, large amount of micro-scaled devices have been invented to achieve novel functions that conventional equipments cannot achieve, or to replace these expensive, maintenance-ineffective, or inefficient devices. Meanwhile, physical phenomena in micro scale are usually different, or unavailable comparing to these under normal scale, which attract people to find new discoveries in principle or under experimental investigation. Among plentiful research, microfluidics is focusing on physical or chemical properties of fluid in micro scale. As a potential solution for chemical or biological conundrum, it has been extensively investigated domestically and abroad.Electro-osmosis, or electro-osmotic flow (EOF), is the phenomenon that ionized liquid locating in the electric double layer (EDL) drags the electrically neutral liquid under applied external electric field. In the thesis, EOF in a straight channel is measured. Zeta potential is obtained indirectly and used in following numerical simulation. Further experiments are conducted via a cross-straight channel. Linear controlled prototype of microfluidic transporter is demonstrated via EOF in a cross-straight channel.For in-deep investigation, advanced equipments are required in EOF experiment. Micro particle image velocimetry (Micro-PIV) is the most successful tools for micro flow visualization and measurement partly because of the improvement of correlation algorithm. In this thesis, diffraction modeling for optical system of Micro-PIV is investigated for detailed simulation by Monte Carlo method. Single pixel ensemble correlation (SPEC) algorithm as well as bi-directional single pixel ensemble correlation (Bi-SPEC)are developed for dealing with flow field which contains large gradient velocities. Meanwhile, single pixel resolution i.e.the maximal density of velocity vectors is obtained via SPEC and Bi-SPEC algorithm.This work was supported in part by the National Natural Science Foundation of China (50335010).