Abstract
The purpose of this thesis is to research and develop high performance micro-bioreactors applied to enhance DNA hybridization and other biochemical reactions; novel measuring techniques also proposed in this study. There are three major branches in this thesis, including the design, analysis, and verification of the original devices, the invention of measuring techniques as well as the pilot tests concerning biochemical fluidic reactions in the devices. The research results are summarized as follows:A novel micromixer named connected-groove micromixer, CGM with connected grooves across the bottom and the sidewall of the channel has been realized by microfabrication using the specific design of mask patterns; the connected grooves have ability to promote the lateral motion and mass conduction of fluids so as to improve fluidic mixing. CGM-2 induces two co-helical flows in the flow field; the interaction of the flows involves mechanisms of cutting, transport, and mixing fluids. The CGM-2 hence possesses better mixing performance than a common device, slanted-groove micromixer, SGM.Based on the mechanisms involving split-and-recombination (SAR) and chaotic mixing, a novel microreactor named SAR □-reactor was proposed for enhancing biofluidic mixing. The SAR □-reactor with in-plane dividing structure and separated channels enables intensive mass split and transport of fluids occurring in the field so as to induce a strong 3D rotating flow to stretch and distort the material interface. The SAR □-reactor was demonstrated by tests of chemical reactions and of viscous fluidic mixing that has excellent performance superior to that of SGM; the SAR □-reactor could be operated at Reynolds number with a wide range and suitable for viscous fluidic mixing.The thesis reveals a measuring technique for quantification of microfluidic mixing/reaction by using confocal fluorescence microscopy involving original quantification method. A universal index termed mixing quality index (Mqi) was proposed for quantifying mixing patterns that one can reasonable evaluate a mixing lengths of devices. The mixing lengths of devices estimated by this technique are larger and more precise than that by a common dye-blending test. These techniques also facilitate monitoring the behavior of two fluorescence fluids in the devices. Beside, another original measuring technique encompassing micro particle image velocimetry (micro-PIV) and particle-counting method was proposed to simultaneously diagnose species velocities and concentrations. The velocity field is obtained by micro-PIV; the concentration field is obtained by particle-counting method; a mixing index could be derived from a concentration field. For the particle-counting method, a watershed-segmentation algorithm and Gaussian weight function are utilized to amend counting results so as to reduce uncertainty down to ± 4%. 2D and 3D velocity and concentration fields in a T-shaped channel are successfully observed through this technique by taking advantage of confocal fluorescence microscopy. Comparing to the numerical results, the average errors of concentration field, velocity field and mixing index are around 5, 5, and 10%, respectively. The profiles of velocity and concentration fields derived from the experiments are satisfactorily corresponding with the results of numerical simulation.Finally, bio-reaction tests including hybridization/conjugation of two complimentary DNA and of DNA and functionalized gold nano-paticles (Au-NPs) were successfully executed in intentional reaction devices. This study thoroughly exhibited reaction and quantification process by using confocal microscopy with fluorescence resonance energy transfer, FRET principle. It requires tens of seconds to fulfill equilibrium for the reactions in the devices; this reaction duration is much shorter than a conventional static hybridization requiring more than several hours. This demonstrates that the efficacy of mobile conjugation of molecules in the devices; the structural design of the devices indeed reinforce the efficiency of bio-reactions.The main contributions of this thesis comprise realizing novel micromixers/microreactors with high performance and simple fabrication and proffering original measuring techniques, design notions, analytical methods, and insightful viewpoints as significant reference materials for successors and future study. Hopefully, through the content of this thesis, readers could grasp the evolution of this study field and then be inspired to create foresighted research.