Research Of Staggered Oriented Ridges Micromixer Based On Chaotic Advection

The leading development trend of modern analytical instrument is miniaturization, integration and portability. Microfluidic chip is primarily based on analytical chemistry, analytical biochemistry, and supported by the manufacturing technology of MEMS. MicroChannel net is the structure characteristic of microfluidic chip, which connects functional elements of actuate, control and detection. Microfluidic chip is the developing focus of micro total analysis system. A micromixer is an important part of microfluidic system, whose function is to realize effective mixing. The micromixer should possess compact structure to be easy fabricated and integrated into microfluidic system. The micromixer should also take up as little space as possible. The output flow rate and concentration should both be adjustable so the output is exactly what is desired. Finally, the micromixer should demonstrate good inherent security.A novel three-dimensional static micromixer, called SOR micromixer, is put forward which was designed according to the characteristic of mixing liquids on the microscale. The device was fabricated on glass substrates using wet-etching technique. Under a steady axial pressure gradient, staggered oriented ridges arranged periodically in microchannel can generate transverse and three-dimensional flow. Chaotic advection is induced in the microchannel, which stretches and folds material interface and passively enhances fluid mixing. The computational fluid dynamics method (CFD) was used to analyze distribution rule of velocity field in the SOR micromixer. Through computation and experiment visualization methods, the optimal structure parameters have been found and the impact of Reynolds number on mixing performance was analyzed. The value of pressure drop of the micromixer was evaluate through the method which computing the ratio of pressure drop between the micromixer and the straight microchannel with the same cross section and length as the micromixer. Finally, the three-dimensional velocity field in the micromixer was regarded as nonlinear dynamic system, and the characteristic of chaotic mixing in the micromixer was studied with Lagrangian tracer tracking techniques. According to the study, staggered oriented ridges arranged periodically in microchannel surely induce chaos phenomena to achieve mixing in microscale. The micromixer possesses compact structure, and its fabrication process is compatible with the technology of MEMS. At the same time, the substrate material is not limit to glass. So a new choice of good passive mixing method was provided.In chapter 1, the background of the microfluidic system and the relevant knowledge of MEMS were reviewed. The different types of micromixer, designing mechanisms,...