Preparation Of Microcapsules Based On The Digitalization Of Microfluids Technology And Design Of The Matching Microfluidic Devices

Along with the rapid development of the microcapsules technology and discipline-crossing, the application fields of microcapsules keep expanding, and the quality requirement of microcapsules has become higher and higher. Although there are a lot of methods for microcapsules preparation, in practical fields of controlled-releasing, there are some bottlenecks such as better controlling of the preparing process, reducing the particle size and reducing its distribution. Therefore problems in method of particle formation, designing and fabrication of the core microfluidic components and method for driving microfluid should be well solved.There are some creative theories in the digitalization of microfluids technology, which exploits the field of the digital matter transportation, equaled with the digital information, the digital energy transmission or solid movement. Pulsating flow of microfluid has been realized in the microfluidic components by using the technology. The research foundation of this paper is the digitalization of microfluids technology, and the research directions are the digital preparation of monodispersed emulsions and microcapsules. The creative achievements on the theoretic research of microcfluid driving, the designing of the method and equipment for fabricating novel microfluidic components, and the digital preparation of emulsions and microcapsules are described as follow.A new method of preparing monodisperse double emulsions and microcapsules is proposed on the basis of digitalization of microfluids technology. Double emulsions of type (O₁/W/O₂) and microcapsules with both liquid and solid core have been prepared. The rhythm of the preparing process could be either sequential or encoded, therefore the process was provided with a digitalized and volume controllable character. The number of particles could be counted and controlled, and the size distribution of the micro-droplets was narrow.The influencing factors of digital micro-jetting of the inner diameter changing micropipette were summarized, and the stability diagram of micro-jetting which based on the summarizing was designed. On the basis of the diagram, the quantitative index of stability for digital micro-jetting was proposed. The process of micro-jetting occurred in the micropipette was observed, which based on the experiments of fluid trace. After the induction of the features of micro-jetting, the author put forward the model of the micro-jetting. It was found that the inertial force, elastic force and viscous force act in the micropipette in turn. On the basis of the model, method of mathematical analysis similar with acoustics was used to analyze the flow field in the micropipette. Therefore the theoretic opinion for improving stability of micro-jetting could be obtained by the analyzing, and practical problems of stable micro-jetting of high-viscosity liquid had been solved.A new Non-IC method for fabricating two-dimensional vitreous microfluidic components is proposed, which is based on the theory of hot rheologic deformation. In the drawing process, reservoirs which connect the microchannels with conical pipes formed. The cross sections of the microchannels are round or dumbbell with no handle, and the walls of the three microchannels connect smoothly in the joint, so there is no dead volume. High quality surface of the microchannels are obtained due to the surface tension. The process has characteristics of low cost, simple manipulation and safe process. On the basis of the prodess, puller for fabricating such three-way microchannels with equal or unequal inner diameter was designed. Method for fabricating microchannel networks was also designed, and three basic microchannel networks had been made.After the technological improvement, the three-way micropipette embedded with another micropipette was designed. Micro-jetting equipment taking the compound micropipette as the core was fabricated, and then followed with experiment of microencapsulation. The effective content of the prepared microcapsules improved obviously.This paper also provides a new method for fabricating in-line multi-micropipettes, which is compatible with digitalization of microfluids technology. Experiments of micro-jetting and microcapsules preparation were carried out by using the micropipettes. The results showed that the efficiency of the micro-jetting and microcapsules preparation improved obviously.