Interfacial control of transport applications

该发现计划旨在为三种传输应用创建一类新的界面操作：蒸发，（滑）电渗透和电渗析。这些过程是无所不在和根本性的，影响着水和可持续能源技术的应用。 关于热传输，第一个项目的目的是通过改变基底的润湿性和（热）传导性来控制干燥液滴中的颗粒排列。系统的实验测量温度分布和三维流场引起的蒸发在一个表面上的固着干燥液滴将进行。目前缺乏的这一关键数据将有助于使用简单而强大的蒸发方法对表面上的材料进行分类和排列的最佳设计。 为了增强动量和电荷传输，在第二个项目中，将设计和生成一种新型的改性超疏水表面，用于微流体的减阻，这是一个长期存在的挑战。将制造具有纵向微槽的疏水微通道，以在微结构上捕获气相流体，从而产生无剪切界面，从而减少壁摩擦。本研究将探讨流场的高解析度，并探讨气液界面的几何形状对微流体滑移的影响。在类似的物理机制下，荷电气液界面上的电荷/离子输运增强是预期的。然而，没有这样的实验验证存在。因此，我将研究相关的电气和流体动力学的影响，通过修改超疏水通道的电荷选择性与电极。 采用离子传输，各种水和能源技术使用电荷选择性表面或膜操作。例如，电渗析是用于脱盐和水净化的广泛使用的方法。在电渗析中，离子在电强制下在电荷选择性表面附近形成浓度梯度，这又限制了离子传输。第三个项目通过实验研究离子浓度梯度引发的流体动力学过程来解决电渗析的这一限制步骤。将进行高分辨率的电场、离子浓度和流场测量，以了解它们之间复杂的相互作用，从而实现高效的电渗析性能。

This Discovery program is directed towards creating a new class of interfacial manipulation for three transport applications: evaporation, (slippery) electro-osmosis, and electrodialysis. These processes are omnipresent and fundamental, influencing applications in technology of water and sustainable energy. Concerning heat transport, the first project aims at controlling particle arrangement in a drying droplet by varying substrate properties of wetting and (thermal) conductivity. Systematic experimental measurements of temperature profiles and 3D flow fields induced by evaporation in a sessile drying droplet on a surface will be carried out. This crucial data, which is currently lacking, would shed light on optimal design for sorting and arranging materials on surfaces, using the simple and powerful method of evaporation. To enhance momentum and charge transport, in the second project, a new type of modified superhydrophobic surfaces will be designed and generated for drag reduction in microfluidics, which is a long-standing challenge. Hydrophobic micro-channels with longitudinal microgrooves will be fabricated to entrap gas phase fluid—creating shear-free interfaces—upon the microstructures, resulting in the reduction of wall-friction. The high-resolution of flow field will be probed; the effect of geometry of gas-liquid interfaces on microfluidic slippage will be experimentally investigated. Under a similar physical mechanism, enhancement of charge/ion transport on charged gas-liquid interface is expected. However, no such experimental verification exists. I will hence examine the associated electrical and fluid dynamical effects by modifying the superhydrophobic channels to be charge-selective with electrodes. Employing ion transport, various water and energy technologies are operated using charge selective surfaces or membranes. For instance, electrodialysis is a widely used method for desalination and water purification. In electrodialysis, ions develop concentration gradients adjacent to a charge selective surface under an electrical forcing, which in turn limits the ion transport. The third project tackles this limiting step of electrodialysis, by experimentally examining the hydrodynamic processes triggered by the gradient of ion concentrations. High-resolution measurements of electrical, ion concentration and flow fields will be conducted to understand their complex interplay for efficient electrodialysis performance.