| Summary: | 碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 95 === In this study, micro-electro-mechanical system (MEMS) technique is applied to fabricate microfluidic emulsion chips. There are three research themes in this thesis.
1. Development of a single-emulsion chip with pneumatic perturbation
We investigate the influence of pneumatic perturbation on dispersed phase fluid for 2D hydrodynamic focusing structure. Experimental results show that the transition time to produce droplets can be reduced greatly from more than 30 minutes to less than 2 minutes.
2. Two-step emulsification with two-dimentional hydrodynamic focusing regions.
By cascading two hydrodynamic focusing regions of 2D structures, double emulsion droplets can be generated. The coefficients of variation for inner and outer droplets are less than 5%.
3. Two-step emulsification with three-dimentional hydrodynamic focusing regions.
In order to overcome surface wetting problem associated with 2D hydrodynamic focusing structures, we design emulsion chips with 3D structures. Our major innovation in this study is to combine optic fiber in the process of photolithography to produce circular microchannel mould. This mold can then be used to replicate circular microchannel with PDMS. Since PDMS is a soft material, there will be a crack on three-dimentional structure while demolding. However, the crack can be recovered during the process of thermal bonding of PDMS components, for PDMS molecules would osmose into the crack. Therefore we can reproduce circular microfluidic channels by PDMS demolding process. We successfully fabricate emulsification chips with three-dimentional hydrodynamic focusing regions to produce double-emulsion droplets.
Our results not only confirm our research ideas, but also exhibit the possibilities of practical applications in emulsion industry.
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