Research On Turbulence Effect Of Spiral Structure Micromixer

Microfluidic technology refers to the use of microchannels to process or manipulate tiny fluids.It is a new interdisciplinary subject involving chemistry,fluid physics,microelectronics,new materials,biology and biomedical engineering.Microfluidic devices are also known as lab-on-a-chip or micrototal analysis systems.Micromixer is an important functional device in microfluidic chip,which has great significance in chemical synthesis,analysis,drug delivery,nucleic acid sequencing and other fields.Micromixer refers to a microfluidic device which realizes the rapid homogenization of sample mixing in a microchannel or microchamber.Micromixers are divided into active micromixers and passive micromixers according to whether the sample mixing needs to be completed by external force sources.The active micromixer needs to mix samples with external force sources.Passive micromixer can realize sample mixing without external force source.Firstly,this paper proposes a flexible microfluidic chip manufacturing method combining 3D printing and polymer material dissolution technology.In this method,a preshaped soluble HIPS channel mold was fabricated by 3D printing technology,and the printed mold was solidified in a PDMS molten solution to form a micro-mixer.The cured micromixer was then immersed in limonene material to dissolve soluble HIPS channel molds to form microchannels.Then the preparation process optimization experiment was carried out.Experimental results show that the HIPS dissolution rate of 0.2*0.2*8mm HIPS channel mold increases with the increase of water bath heating temperature.The dissolution rate is the fastest when a 100℃ water bath is heated,and the dissolution is completed in 30 minutes.Under the heating condition of a 100℃ water bath,with the decrease of solubility difference,the dissolution rate increases.Under the condition of 50% limonene,the HIPS dissolution rate is the fastest and can be completely dissolved in 25 min.Finally,the optimal dissolution condition is 100℃ water bath heating,50% limonene concentration.Compared with the existing chip processing technology,this method has the advantages of a simple manufacturing process,no key sum,and high chip strength.It is of great significance to the fabrication of microfluidic chips.Secondly,based on this manufacturing technology,a spiral 3d passive turbulent micromixer is proposed.The mixing efficiency is improved by using a spiral structure to produce a turbulence effect.The mixing experiment shows that under the same conditions,the mixing efficiency of the single spiral structure can be improved to 0.85 compared with that of the common T-shaped planar channel of 0.78.Three screw diameters,three screw number structures,and different flow rates were used to test the mixing effect.The optimal spiral structure is a 5mm structure and the flow rate is 2.0 m L /min.Finally,the mixing efficiency of the 3d spiral micromixer can reach 0.948.The results show that the three-dimensional spiral structure can effectively improve the mixing efficiency.Thirdly,after the preparation of a single spiral 3d passive turbulent micromixer,the spiral structure parameters were optimized by simulation and experiment.Finally,the optimal mixing structure and optimal mixing conditions are obtained.With the increase of flow velocity,the turbulence effect can be effectively improved and the mixing efficiency can be improved.The experimental results show that the mixing efficiency can be improved to 0.88 by using single helix structure.With the increase of the number of spiral structures,the mixing efficiency of the three-spiral structure turbulent micromixer can reach 0.9.When the flow rate was 2m L/min,the optimal mixing efficiency was 0.90.The results show that the spiral 3d passive turbulent micromixer can effectively improve the fluid mixing efficiency.The optimal mixing efficiency is 0.95.Finally,the performance of the micromixer is tested and the flow experiment of the chip is carried out.The conclusion is as follows: compared with the t-shaped straight channel with the same length and cross-sectional area of the channel,the three-dimensional spiral structure can increase the mixing efficiency compared with the plane structure at the same flow rate.It is proved that the three dimensional spiral turbulence effect micromixer made by the method in this paper contributes to the research of micro-nano fluidic chip.