生物芯片中周期性电渗驱动液体薄膜的流动特性

FLOW CHARACTERISTICS OF LIQUID FILMS DRIVEN BY PERIODIC ELECTRO-OSMOSIS IN BIOCHIPS

研究了二维周期性电渗驱动液体薄膜的流动特性.以Debye-H(u|¨)ckel假设近似下线性化的Poisson-Boltzmann方程描述双电层电动势分布和电荷密度的分布关系,与黏性不可压缩流体Navier-Stokes方程相耦合,得到流体在自由面与固壁之间的周期电渗流流场的精确解.结果显示,薄膜内速度振幅与流体黏性密切相关,雷诺数越大,速度振幅就越小.该文还细致分析了雷诺数和自由面ζ电势对自由面的流速振幅和薄膜内速度相位差的影响.

The flow of a thin film on a solid substrate driven by periodic electro-osmosis is studied in the present paper. To describe the relation between potential of electric double layer and charge density, the Poisson-Boltzmann equation is utilized under the Debye-Hiickel approximation. An analytical solution for the film is obtained by solving the periodic electro-osmosis driven system, coupling with the Navier-Stokes equation for incompressible viscous fluid. Results indicate that amplitude of the flow velocity in the thin film strongly depends on the Reynolds number, i.e., the amplitude decreases as the Reynolds number increasing. The influence of the 4 potential, as well as the viscosity, is also analyzed on the flow velocity at the free surface and phase difference of the oscillating velocity.