The Theory and Experimental Study about Microfluid Pumping in Point Plane Electrode System
|School||Harbin Institute of Technology|
|Course||Mechanical Design and Theory|
|Keywords||point plane electrode microfluid driving electrochemical ac electrothermal flow reversal|
Lab-On-a-Chip (LOC) based on micro electromechanical system (MEMS) techniques is a new mode for experiment research, and has expansive application prospect in areas of biochemistry, medicine, printing, chip cooling, etc. Microfluid driving is crucial in research of LOC, in which research of microfluid driving caused by electric field has aroused wide concern because of its advantages like high efficiency, high reliability, low costing and easily integrated with other fluid devices. On basis of former research, this thesis studies the mechanism of point plane electrode that bases on theory of microfluid driving caused by electric field, analyzes the primary factors that influence the flow, explained the phenomenon of flow reversal, which betrays the theory of ACEO, using theory of electrochemistry. And the study result is verified through emulation and experiments.Summarizes the home and abroad research statuesque of DCEO and ACEO, analyzes basic mechanism of ACEO, electrochemistry and AC electrothermal, explains reasonably the phenomenon of the microfluid flowing under electric beyond relaxation frequency and flowing in opposite direction, which can not be explained by theory of ACEO, studies the primary cause of flowing under various frequencies, and derives separately velocity formulas of microfluid flowing under effect of electrochemistry and AC electrothermal.Based on the theoretical analysis, 3D simulation model of point plane electrode system is proposed. The electric field and flow field of point plane electrode are simulated through solving of the equations like Laplace, electric charge conservation, conduction and diffuse, energy balance and Navier-Stokes with electrodynamic force or electrothermal force. The primary cause of flowing under low or high frequencies is qualitatively analyzed.In order to validate the exactitude of the theoretical study and the simulation results, the micro-particle polystyrene with 0.5μm diameters used in point plane electrode system platform for experiments of flow in opposite direction, electrochemistry proving, and velocity comparing. And results from theoretical and simulation analysis are verified correct.The primary cause of flow under various frequencies is studied theoretically and experimentally to reach the conclusion of electrochemistry’s leading role of microfluid driving in point plane electrode system.