Interfacial control of transport applications

这一发现计划旨在为三种传输应用创造一种新的界面操纵：蒸发、(湿)电渗透和电渗析。这些过程是无处不在的和基本的，影响着水和可持续能源技术的应用。 关于热传输，第一个项目旨在通过改变基材的润湿和(热)传导性来控制干燥液滴中的颗粒排列。对固着干燥液滴表面蒸发引起的温度分布和三维流场进行了系统的实验测量。这一目前缺乏的关键数据将有助于使用简单而强大的蒸发方法在表面上对材料进行分类和排列的优化设计。 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来用于微流体的减阻，这是一个长期存在的挑战。具有纵向微槽的疏水微通道将被捕获气相流体--产生无剪切界面--在微结构上，从而减少壁面摩擦。探讨了流场的高分辨率，实验研究了气液界面几何形状对微流体滑移的影响。在相似的物理机制下，荷电气液界面上的电荷/离子输运有望得到增强。然而，并不存在这样的实验验证。因此，我将通过将超疏水通道修改为具有电极的电荷选择性来研究相关的电学和流体动力学效应。 利用离子传输，各种水和能源技术使用电荷选择表面或膜进行操作。例如，电渗析是海水淡化和水净化的一种广泛使用的方法。在电渗析中，离子在电强迫下在电荷选择表面附近形成浓度梯度，这反过来限制了离子的传输。第三个项目解决了电渗析的这一限制步骤，通过实验检查了离子浓度梯度引发的流体动力学过程。将对电场、离子浓度和流场进行高分辨率测量，以了解它们对于高效电渗析性能的复杂相互作用。

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.