Joule Heating Effects on Two-phase Flows in Dielectrophoresis Microchips
Joule Heating Effects on Two-phase Flows in Dielectrophoresis Microchips
复制标题
介电泳微芯片中两相流的焦耳热效应
DOI：
10.1007/s13206-017-1209-9
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发表时间：
2017-09-20
期刊：
影响因子：
4.3
通讯作者：
Wen, Shizhu
中科院分区：
文献类型：
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作者：
Yan, Ying;Guo, Dan;Wen, Shizhu
焦耳加热是基于微流体器件的一个重要现象，这是由于电极周围电场的局部放大。这将导致微通道内的温度升高，从而影响微通道内样品的生物活性。本文建立了一个考虑焦耳热效应、电场和流场的介电泳微芯片两相流场动态特性的数值模拟模型。采用实验方法验证了模型的合理性，并详细研究了微芯片在交流和直流电场作用下的焦耳热效应。在数值模拟部分，比较了交流电场和直流电场的差异。结果表明，在相同的有效电压下，直流电场可以产生更多的焦耳热，并在微通道内获得更高的温度。这是由于直流电场中电极周围的电场强度比交流电场中的强。其次，研究了分散相和连续相流速对温度的影响，发现温度随流速的增加而降低。此外，它被发现，焦耳热效应提高液滴速度的基础上的结果。最后，应用红外摄像机对微通道的热特性进行监测，以保证数值模拟的合理性。这些结果预计将提供有益的指导，为未来的设计，将避免焦耳热效应或利用焦耳热效应的基于双金属的微器件。
Joule heating is a significant phenomenon in dielectrophoresis-based microfluidic devices due to the local amplification of the electric field around electrodes. This leads to the temperature rising in microchannel which would influence the bioactivity of samples in the microchannel. In this paper, a numerical simulation model considering joule heating effect, electric field, and flow field is proposed to describe dynamic behaviors of two-phase flows of the dielectrophoresis microchip. The experimental methods are applied to verify the rationality of model and joule heating effects on microchips under both AC (Alternating current) and DC (Direct current) electric fields are investigated in detail. In numerical simulation part, the difference between AC and DC electric fields is compared. According to the results, it is found that with the same effective voltage, DC electric field can generate more joule heat and flow in the microchannel obtained higher temperature. This is caused by that the electric field strength around the electrodes in the DC electric field is stronger than that of the AC electric field. Secondly, effects of dispersed phase and continuous phase flow velocity are investigated and temperature will decrease with the increasing of flow velocity. Also, it is found that the Joule heating effects improve the droplet velocity based on the results. Finally, an infrared camera is applied to monitor the thermal characteristics of the microchannel to ensure that the numerical simulation is reasonable. These results are expected to provide useful guidance for future designs of dielectrophoresis-based microdevices that will avoid joule heating effects or take advantage of joule heating effects.