Joule heating and heat transfer in poly(dimethylsiloxane) microfluidic systems
Joule heating and heat transfer in poly(dimethylsiloxane) microfluidic systems
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DOI：
10.1039/b306158b
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发表时间：
2003-01-01
期刊：
影响因子：
6.1
通讯作者：
Li, DQ
中科院分区：
文献类型：
--
作者：
Erickson, D;Sinton, D;Li, DQ
焦耳加热是电动驱动微流控芯片中的一个重要问题，尤其是聚合物系统，在这些系统中，低导热系数放大了拒绝这种内部产生的热量的难度。在这项工作中，使用实验(使用微尺度测温技术)和数值(使用三维“全芯片”有限元模型)相结合的方法来研究聚二甲基硅氧烷(PDMS)和PDMS/玻璃混合微流控系统中微通道交叉口的焦耳加热和换热。总的来说，数值预测和实验结果非常吻合(通常在+/-3摄氏度以内)，在交叉点处都显示出显著的温度梯度。在高势场强下，观察到PDMS/PDMS芯片的最高缓冲温度是PDMS/Glass系统的近5倍。详细的数值分析表明，绝大多数稳态散热是通过芯片的下层基板进行的，而在前者情况下，热导率较低的PDMS基板会显著阻碍这一过程。观察到的较高的缓冲温度也导致了一些显著的次要影响，包括体积流量几乎翻了一番。提出了改进聚合物芯片设计并由此扩展这些微流控系统的能力的简单指南。
Joule heating is a significant problem in electrokinetically driven microfluidic chips, particularly polymeric systems where low thermal conductivities amplify the difficulty in rejecting this internally generated heat. In this work, a combined experimental (using a microscale thermometry technique) and numerical (using a 3D "whole- chip" finite element model) approach is used to examine Joule heating and heat transfer at a microchannel intersection in poly(dimethylsiloxane) (PDMS), and hybrid PDMS/Glass microfluidic systems. In general the numerical predictions and the experimental results agree quite well (typically within +/-3degreesC), both showing dramatic temperature gradients at the intersection. At high potential field strengths a nearly five fold increase in the maximum buffer temperature was observed in the PDMS/PDMS chips over the PDMS/Glass systems. The detailed numerical analysis revealed that the vast majority of steady state heat rejection is through lower substrate of the chip, which was significantly impeded in the former case by the lower thermal conductivity PDMS substrate. The observed higher buffer temperature also lead to a number of significant secondary effects including a near doubling of the volume flow rate. Simple guidelines are proposed for improving polymeric chip design and thereby extend the capabilities of these microfluidic systems.