Mechanism Analysis Of Electroconvection In Microfluid System And Experiment Research

Microfluidics is a high and new technology with rapid growth of MEMS, which is integrated in a small chip with sample preparation, biochemistry reaction, separation and detection, in order to achieve different biochemistry reaction and the analysis of product. Considering this technology has extensive potential in biochemistry reaction, environmental monitoring, medical transport, etc. Microfluid driving is the most important component in the microfluidic chip system, which can fulfill the purpose of precise manipulation of microfluidics, power supply of microsystem and sample delivery effectively. Therefore, the research on it has important significance in theory and practice.Electroconvection is the phenomenon of fluid flow in micro scale caused by concentration gradient of ions in different part of microsystem in the study of microfluid driving based on electric field mechanism. This factor has a great effect on the experiment results in the study of microfluidic chip system. This paper, taking this as starting point, thorough analyzes the mechanism of electroconvection phenomenon.Paper summarized the microfluid driving technology domestic and foreign research present situation. This paper revealed the basic mechanisms of electroconvection fluid flow according to the mechanisms of DC electroosmosis and AC electroosmosis micro fluid drive and based on the basic principles of electrochemical reaction. This paper supply a reasonable analysis on the phenomenon of flow reversal, which betrays the theory of ACEO, study the effect of electroconvection in different parameter, and forecast the experiment phenomenon of electroconvection in different conditions.Based on the theoretical analysis of electroconvection, 2D simulation model of electroconvection parallel-plate electrode system is established, the relevant control equations and boundary conditions is set up. The electric field, concentration field and flow field of electroconvection parallel-plate electrode system are simulated through solving of the equations such as electric charge conservation, conduction and diffuse and Navier-Stokes. This study provides a simulation foundation for experimental research.Electrochemical reaction is the foundation of generate electroconvection in micro-cavity. The experiment of current density is one of the most effective methods to detect electrochemical reaction taken place in solution. Electrochemical reaction usually result in PH change in solution. This paper use fluorescein dye to measure the distribution of PH in solution. This study provides a experiment foundation for the electroconvection mechanism research.Electroconvection is a new method to collect particles. Polystyrene particles with diameters of 0.5μm and 3μm were used as experimental objects to study the rapid collection of particles under direct electric fields. Experiments show that this method can achieve a good effect in collect particles with diameter of several microns. This methold has a simple structure and a rapid collection speed. Analysis of the velocity fluid flow in electroconvection is the key to the studying of electroconvection. Using fluorescence microscopy to observe the micro fluid flow in electroconvection, to measure the velocity of micro fluid flow in electroconvection at different parameters. Then, the results of experiments and simulations have been compared to testify the theoretical analysis of simulation.