Tang Gongyue, Yang Chun
Institute of Microelectronics, Singapore Science Park II, Singapore, Republic of Singapore.
Electrophoresis. 2008 Mar;29(5):1006-12. doi: 10.1002/elps.200700714.
Temperature gradient focusing (TGF) is a recently developed technique for spatially focusing and separating ionic analytes in microchannels. The temperature gradient required for TGF can be generated either by an imposed temperature gradient or by Joule heating resulting from an applied electric field that also drives the flow. In this study, a comprehensive numerical model describing the Joule heating induced temperature development and TGF is developed. The model consists of a set of governing equations including the Poisson-Boltzmann equation, the Laplace equation, the Navier-Stokes equations, the energy equations and the mass transport equation. As the thermophysical and electrical properties including the liquid dielectric constant, viscosity, and electric conductivity are temperature-dependent, these governing equations are coupled, and therefore the coupled governing equations are solved numerically by using a CFD-based numerical method. The numerical simulations agree well with the experimental results, suggesting the valid mathematical model presented in this study.
温度梯度聚焦（TGF）是一种最近开发的用于在微通道中对离子分析物进行空间聚焦和分离的技术。TGF所需的温度梯度可以通过施加的温度梯度产生，也可以通过施加电场产生的焦耳热产生，该电场也驱动流体流动。在本研究中，开发了一个描述焦耳热引起的温度发展和TGF的综合数值模型。该模型由一组控制方程组成，包括泊松-玻尔兹曼方程、拉普拉斯方程、纳维-斯托克斯方程、能量方程和质量传输方程。由于包括液体介电常数、粘度和电导率在内的热物理和电学性质与温度有关，这些控制方程是耦合的，因此使用基于计算流体力学（CFD）的数值方法对耦合的控制方程进行数值求解。数值模拟与实验结果吻合良好，表明本研究中提出的数学模型是有效的。
