Research On Fabrication Of Polymer Microfluidic Chips With Complicated Microstructures

Microfluidic chip is one of the important parts of miniaturized total analysis systems (μTAS), and the polymers have been the key material on the fabrication of microfluidic chips. Based on the basic principles of polymers' embossing, the fabrication of various microfluidic chips with complicated micro-structures is researched in this paper.The fabrication method of microfluidic chips with micro-pillars in the micro-channels is presented in this paper, the silicon mold is fabricated by traditional photo lithography and dry etching method, and then the embossing experiments are carried out on the RYJ-I embossing machine. The difficulty on embossing of this microfluidic chip is how to make the polymer fill in the concave cavity of the silicon mold, based on a great deal of embossing experiment datas, the laws of polymer filling in the concave cavity and the influence of each embossing parameter on the PMMA replication accuracy are both discussed. It is indicated through the embossing craft experiment results that the most desirable craft state of concave cavity's filling is appeared when temperature 125℃, pressure 170kg, and keep temperature and pressure for at least 600s. Finally, the simulation of the microfluidic chips embossing with micro-pillars in the micro-channels is employed.The fabrication method of microfluidic chips with high-depth and high-density micro-channels is also presented. In order to achieve high replication accuracy, the effect of main embossing parameters is studied firstly. Then, a method of aided demouding with vacuum is employed; a vacuum device is designed independently aiming to solve the problems of demouding. Consequently, microfluidic chips could be separated from silicon mold automatically. The forces during the demouding process are calculated. And then, the relation of hot bonding parameter and the depth loss of the micro-channels is investigated based on experiments, a method of aided bonding with elastic film is introduced on the basis of optimizing the experiment parameters. The results of simulation and experiments show that the depth loss of the micro-channels could be decreased obviously after the new method employed. Finally, the microfluidic chips with high-depth and high-density micro-channels are fabricated from PMMA successfully through hot embossing and hot bonding.Finally, the fabrication of PDMS microfluidic chip is studied. A microfuidic chip with multi-depth micro-channel is fabricated by PDMS casting, at the same time, the microfuidic chips with micro-pillars are fabricated in the same way. PDMS has a better performance on filling cavity than PMMA through the contrast with the method of hot embossing.