Characteristics Of Internal Flow And Micromixing Performance Of T-shaped Micromixer With Build-in Baffles

As an important pretreatment device of microfluidics chip, micromixer occupies an important position in the lab on a chip.Using micromixer not only reduce the consumption of the precious reagents, but also can accelerate the analysis process greatly, and insure high precision, safe and reliable operation. Micromixer will play an extremely important role for advanced analysis testing technology popularization.How to achieve fast and effective microfluidic mixing, deserve intensively research.This paper studies the characteristics of internal flow and micromixing performance of T-shaped micromixer with build-in baffles and proposes a new micromixer with periodic triangle baffles mounted in the main channel then evaluates its mixing performance using commercial computational fluid dynamics software ANSYS CFX. The analysis of the results of numerical simulation indicate that relative effectiveness of the structure parameters on mixing performance can be ranked as: the angle of baffles attack θ > the microchannel height H > baffles width L > the distance between adjacent mixing unit D. Within the scope of the researched structure parameters can determine the optimal parameter combination for: θ=75°,L=0.7Wm, D=0.6Wm, H=0.4Wm.Numerical simulation results show that the micromixer with optimal parameter combination performance is excellent, when Re>30, the mixing index M>95%, namely is implemented completely mixed.Reduce the baffles section width of Wc, to a certain extent, can improve the mixing performance, but the decrease of the Wc increased the difficulty of processing, and also cause large pressure loss. This paper also studies the present situation of the built-in baffles effect on the performance of micromixer, the results show that when the Reynolds number is higher, set periodic baffles in microchannel can bring more advantageous to the improvement of the micromixing performance. The import structure has significant impact on the performance of hybrid, compared with the common T-type inlet, select cross import structure is more advantageous to the improvement of the performance of the micromixer.According to the results of numerical simulation research, produce micromixer experimental chip with silicon and glass materials by using the MEMS processing technology. Selecte the micromixer which with inside periodic triangle blocks andcross inlets as the experimental components to conduct micromixing experiment.Using the pressure sensor to measure the import and export pressure of the micromixer chip, and then record the micromixing process by high-speed digital camera.Experimental results show that although the experiment measurements of the pressure loss between the inlets and outlet of the micromixer chip and the results of the numerical simulations have a certain relative error, but due to the small variations in relative error, this means that the measurements and the numerical simulations calculation value keep a good consistency. By comparing the hybrid digital photos with numerical simulation of the process of the medium flow tracing line and mixed areas color labels, it can be seen that the experimental results are in good agreement with the numerical simulation, thus proving the validity of the numerical simulation research used in this paper, and the mixing performance of the proposed micromixer.