Tang Gongyue, Yan Deguang, Yang Chun, Gong Haiqing, Chai John Chee, Lam Yee Cheong
School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
Electrophoresis. 2006 Feb;27(3):628-39. doi: 10.1002/elps.200500681.
Joule heating is inevitable when an electric field is applied across a conducting medium. It would impose limitations on the performance of electrokinetic microfluidic devices. This article presents a 3-D mathematical model for Joule heating and its effects on the EOF and electrophoretic transport of solutes in microfluidic channels. The governing equations were numerically solved using the finite-volume method. Experiments were carried out to investigate the Joule heating associated phenomena and to verify the numerical models. A rhodamine B-based thermometry technique was employed to measure the solution temperature distributions in microfluidic channels. The microparticle image velocimetry technique was used to measure the velocity profiles of EOF under the influence of Joule heating. The numerical solutions were compared with experimental results, and reasonable agreement was found. It is found that with the presence of Joule heating, the EOF velocity deviates from its normal "plug-like" profile. The numerical simulations show that Joule heating not only accelerates the sample transport but also distorts the shape of the sample band.
当在导电介质上施加电场时，焦耳热是不可避免的。这会对电动微流控装置的性能造成限制。本文提出了一个关于焦耳热及其对微流控通道中电渗流和溶质电泳输运影响的三维数学模型。使用有限体积法对控制方程进行了数值求解。开展了实验以研究与焦耳热相关的现象并验证数值模型。采用基于罗丹明B的测温技术来测量微流控通道中的溶液温度分布。利用微粒图像测速技术来测量在焦耳热影响下的电渗流速度剖面。将数值解与实验结果进行了比较，发现两者吻合良好。研究发现，在存在焦耳热的情况下，电渗流速度偏离其正常的“塞状”剖面。数值模拟表明，焦耳热不仅加速了样品输运，还使样品带的形状发生了畸变。
