Study On Direct Inkjet Printing Technology For Paper-based Micromixer And Fluid Mixing

Microfluidic chip is a very powerful and practical tool of biological and chemical analysis in MEMS(Micro-Electro Mechanical Systems) disciplines. As an important component of the microfluidic chip,micromixer has a certain improvement in the speed and efficiency of analysis in the microfluidic chip by controlling microfluid mix. However, the traditional production of silicon or glass substrates is time consuming and expensive, so that the microfluidic device is only used in specialized laboratories and unable to promote. The paper-based microfluidic chip can be a good solution, It does not require traditional lithography and subsequent dry and wet etching processing techniques, it fabricate hydrophilic-hydrophobic region on paper substrates through more easier processing techniques. Direct inkjet printing technology can help us to achieve the formation of micro-channel network on paper substrates. Direct inkjet printing technology is that computer assists to design pattern and control machine to eject inks from nozzles on substrates.This paper aims to study on the feasibility of producing paper-based micro-mixer by conventional direct inkjet printing technology and research on the technology of microfluid mixing in paper-based micro mixer driven by DC Voltage.The main content of the full text is as follows:1) Both development of microfluidics and micro-mixer type are briefly introduced. And the mechanism of mixing in micromixer and paper-based microchannel is described. Next, the details of direct inkjet printing technology as well as inkjet printing materials are reviewed. Finally, the current processing of paper-based microfluidics by direct inkjet printing technology is reviewed.2) A method for making paper-based microfluidics based on direct inkjet printing technology is researched. First, the configuration of hydrophobic inkjet inks is handle, hydrophobic material(the main ingredients is resin) is dissolved in ethanol with a certain proportion. If the inappropriate concentration is too high, it could block nozzles. And ultimately the concentration of ink(hydrophobic material:ethanol=1:5) is selected for the experiment. The ink was charged in the modified configured HP inkjet printer. And a computer control the printer to form micro-channel pattern which is designed by computer on the filter paper. The effect of the number of injections and the formation of micro-channel pattern is researched, the results show that in order to form an effective hydrophobic region on the paper surface, the injection must be more than 15 times, but in the opposite of the paper is not formed. In the reverse of paper, the opposite patterns is injected more than five times, it really formed an effective hydrophobic region on the filter paper. Through the above experiments, we have confirmed the feasibility of making paper-based microfluidic chip by ordinary direct inkjet printing technology.3) Three paper-based micro-mixer are designed, manufactured and compared in this paper. There are passive straight-channels Y-type paper-based micromixer ? passive Zigzag-channel Y-type paper-based micromixer and active Zigzag-channel Y-type paper-based micromixer. We define the mixing index through a colour hue-based technique. First, the mixed effects of two different channel passive micromixer are studied. The results show that the mix index of Zigzag-channel is better than straight-channels. Then the mixed effects of passive Zigzag channel micromixer and active Zigzag channel micromixer are studied. the results show that active Zigzag-channel micromixer is superior to the passive Zigzag-channels micromixer and adding 5V is superior to adding 20 V. A model is built about velocity of flow in porous media driven by DC Voltage. Then the relationship between velocity and voltage is discussed in the theoretical and experimental analysis.In conclusion, Studies have shown that the paper-based micromixer fluid mixing driving by voltage is better than paper fibers spontaneous mixing, this thesis has a reference value. to the fluid flow in paper-based microchannel controlled by voltage.