Flow Characteristics Of Microfluidic Fluids In Mixing And Chemical Reactions

Microfluidic technology is mainly aimed at small scale,i.e.,micro-nano scale fluid operation,it has a wide range of applications in micro-nano scale heat transfer,electromechanical equipment miniaturization,biomedical detection and chemical analysis and other fields.The study of microscale fluid flow characteristics is the key to the realization and development of this technology.The total internal reflection fluorescence microscopy system and microfluidic chip operating system is combined.Evanescent wave is used as illumination system because of the characteristics of the exponential decay of intensity index with lighting depth.Flow characteristics of T-microfluidic chip internal flow and mixing and chemical reaction under low Reynolds number are studied with the MnPIV technology.In order to understand the difference between the flow in a square microchannel and that in a macroscopic flow,the velocity distribution of water in a fully developed flow in a single channel at different inlet flow rates is calculated,and compared with the theoretical Poiseuille flow,it is found that the axial velocity distribution under large velocity is "sharp" than that in the theoretical Poiseuille flow.Based on the existing 3D partitioning technology,the partitioning range is limited to the T-shaped field of view.The flow information of the fluid in the T-shaped microchannel is obtained by studying the flow at different inlet flow rates and the flow with chemical reaction.By fitting the precursor height of the mixing of water at the junction of inlet and outlet channels,the evolution of water mixing in a short time is obtained.The velocity distribution during mixing is calculated.It is found that there are two almost identical fully developed peak velocities at the initial stage of mixing and the velocities fluctuate in the developing stage.The distribution of tangential velocity at the outlet is consistent with the fluctuation of axial velocity at different flow rates.When there is a chemical reaction,it is found that the velocity distribution at the exit channel fluctuates more and is proportional to the degree of chemical reaction.At the same time,chemical reaction has a greater effect on tangential velocity,and the greater the concentration of the reactants,the greater the tangential velocity.Finally,the relationship between the chemical reaction rate and the height of the precursor and the concentration of the reactants is obtained through the complete reaction of the local field of view.