| With the development of life science, analytical science and other relevant subjects, the demand for microfuidic device is increasing quickly. How to fabricate the disposal microfluidic device of high quality fast has become one of the hottest topics in research field. Flexible technology with its unique advantages has been widely applied in many areas. The flexible microfluidic device based on flexible technology has advantages including good mechanical properties, low thermal resistance, high thermal efficiency, low cost etc. However, most of the present study of both international and domestic academics are launched based on rigid microfluidic device, there were little researches about flexible microfluidic device. Consequently, in this paper, a method of rubber-assisted hot embossing flexible microfluidic device is putted forward based on flexible polymer film. On this basis, The comprehensive exploration and research about the simulation analysis of hot embossing, the design and manufacturing of hot embossing mold, the process of hot embossing, the bonding process of flexible microfluidic device, the mixing performance of micromixer are carried on. The details are as follows:Firstly, the simulation analysis of rubber-assisted hot embossing process is carried on using finite element method(FEM). The two parameters Mooney-Rivlin equation is selected as the constitutive model of PS films at110℃and the rubber. When the temperature is90℃and100℃, the linear elastic model is chosen as the simulation model of PS films. Then the influence of temperature, pressure and rubber hardness to the quality of microchannel is analyzed respectively. The results show that, the channel depth increases as the increase of temperature, the enlargement of pressure or the decrease of rubber hardness. However, the channel thickness becomes worse with the increase of temperature. The mean value of thickness is larger, and the pressure or the rubber hardness has little effect to channel thickness at90℃. But The average thickness value is smaller, and the channel thickness starts to deteriorate as the increase of pressure or the decrease of rubber hardness at110℃Secondly, one type of hot embossing mold was designed and manufactured. The mold is composed of upper mold and lower mold. There is a blind hole designed on the lower mold. This design can not only prevent the lateral movement of rubber, but also ensure that the upper mold moves merely in the vertical direction. The microchannel on the upper mold was fabricated by wire electrical discharge machining(WEDM) based on its special shape and feature.Thirdly, the effect of temperature, pressure and rubber hardness to the quality of microchannel is researched using single factor experiment. Also the experimental results and the simulation results are compared and analyzed. The experimental results and simulation results indicate a consistent trend, and then the correctness of the simulation model is demonstrated. On this basis, the temperature90℃, the pressure20kN, and the rubber hardness30A is proved to be the optimal process parameters in rubber-assisted hot embossing, the channel depth is99.5pm, the channel width is199.4μm, the mean value of channel thickness is23.98μm, and the variance of channel thickness is0.102under this circumstances. Solvent-assisted bonding is selected as the bonding method, when the temperature is40℃and the pressure is5kN, the PS and PC film bond effectively.Finally, the relationship between mixing performance and Reynolds number(Re) of flexible micromixer molded by hot embossing was studied using Fluent software. The results show that fluid can mix well when the Reynolds number is lower or higher. However, the higher Reynolds number of mixing is chosen in this paper considering the efficiency. |
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