圆微通道内压力驱动流的流动电位及动电效应  

Streaming Potential and Electrokinetic Effect of the Pressure-Driven Flow in the Circular Microchannels

作　　者：刘莹[1] 王路鹏[1] 谭德坤[1,2] 

机构地区：[1]南昌大学机电工程学院,南昌330031 [2]南昌工程学院信息工程学院,南昌330099

出　　处：《微纳电子技术》2014年第5期308-314,共7页Micronanoelectronic Technology

基　　金：国家自然科学基金重点项目(50730007);国家自然科学基金项目(51165031)

摘　　要：采用流动Navier-Stokes方程和双电层电位的Poisson-Nernst-Planck方程建立压力驱动圆形微通道内电解质溶液流动的数学模型,根据电流平衡条件求得流动电位场。应用有限元法分析了离子浓度、压力梯度及通道特征长度对流动电位的影响规律。在此基础上,进一步分析流动电位引起的动电效应对微流动的影响。结果表明:随着压力梯度的增大或离子浓度的减小,流动电位增大;随着特征长度的增大,流动电位先是急剧增加然后逐渐减小;动电效应阻滞作用随着特征长度或离子浓度的减小而增大,与驱动压力无关;低离子浓度溶液在较小特征长度通道中流动会出现局部"回流"现象,其根本原因是流体剪切力方向发生了改变。A mathematic model of the electrolyte flow in the pressure-driven circular microchannels was established by the Navier-Stokes equation for liquid flow and the Poisson-Nernst-Planck equation for electric double layer potential,and the streaming potential field was obtained based on the current balance condition.The effect rules of the ion concentration,pressure gradient and channel characteristic length on the streaming potential were analyzed by the finite element method.On this basis,the influence of the electrokinetic effect caused by streaming potential on the micro-flow was further analyzed.The results show that the streaming potential increases with the increase of the pressure gradient or the decrease of the ion concentration.The streaming potential increases rapidly at first and then slowly decreases with the increase of the characteristic length.The retardation of the electrokinetic effect increases with the decrease of characteristic length or ion concentration,regardless of the driving pressure.The phenomenon of the partial ＂reflowing＂ in the small characteristic length channel occurs for the low ion concentration solution,and the fundamental reason is that the direction of the fluid shear stress changes.

关 键 词：动电效应 流动电位 离子浓度 压力梯度 特征长度 

分 类 号：O35[理学—流体力学]