Mukherjee Siddhartha, Dhar Jayabrata, DasGupta Sunando, Chakraborty Suman
Advanced Technology Development Center, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
Proc Math Phys Eng Sci. 2019 Jan;475(2221):20180522. doi: 10.1098/rspa.2018.0522. Epub 2019 Jan 9.
Augmenting the dispersion of a solute species and fluidic mixing remains a challenging proposition in electrically actuated microfluidic devices, primarily due to an inherent plug-like nature of the velocity profile under uniform surface charge conditions. While a judicious patterning of surface charges may obviate some of the concerning challenges, the consequent improvement in solute dispersion may turn out to be marginal. Here, we show that by exploiting a unique coupling of patterned surface charges with intrinsically induced thermal gradients, it may be possible to realize giant augmentations in solute dispersion in electro-osmotic flows. This is effectively mediated by the phenomena of Joule heating and surface heat dissipation, so as to induce local variations in electrical properties. Combined with the rheological premises of a viscoelastic fluid that are typically reminiscent of common biofluids handled in lab-on-a-chip-based micro-devices, our results demonstrate that the consequent electro-hydrodynamic forcing may open up favourable windows for augmented hydrodynamic dispersion, which has not yet been unveiled.
在电驱动微流控装置中，增强溶质种类的扩散和流体混合仍然是一个具有挑战性的问题，这主要是由于在均匀表面电荷条件下速度分布具有固有的类似塞状的性质。虽然对表面电荷进行明智的图案化处理可能会避免一些相关挑战，但溶质扩散的相应改善可能微乎其微。在此，我们表明，通过利用图案化表面电荷与固有诱导热梯度的独特耦合，有可能在电渗流中实现溶质扩散的巨大增强。这有效地由焦耳热和表面热耗散现象介导，从而引起电学性质的局部变化。结合粘弹性流体的流变学前提，这通常让人联想到基于芯片实验室的微型设备中处理的常见生物流体，我们的结果表明，由此产生的电流体动力学力可能为增强的流体动力学扩散打开有利的窗口，而这尚未被揭示。
