Elucidating Hydrodynamics at Confined Interfaces for Artificial Active Fluidics and Beyond

构成我们身体的活细胞的表面是由精心设计的小于一纳米（即人类头发直径的万分之一）的微小毛孔组成的。大自然已经进化出这些孔隙，以有效地利用分子间力和表面效应，实现卓越的水/离子选择性和离子传输，甚至与浓度梯度相反。因此，它们在人体肾脏的功能中起着至关重要的作用，可以从血液中清除废物/额外的液体，并允许脑细胞（即神经元）产生大脑感知和计算所需的电脉冲。例如，浓度梯度驱动离子穿越神经元细胞膜产生电信号，并以每秒几十米的速度作为一种通信手段进行传输。拟议的研究旨在在实验室中制造类似的孔隙，以制造(i)人工流体装置，使细胞之间可以用它们的语言直接交流（交换离子/水分子），以及（ii）通过将淡水与海水混合来产生能量的膜，以及在产生最少二氧化碳的情况下高效地从海水中去除盐。与水在花园软管中的流动不同，流体在纳米级孔隙中的运动物理学几乎不为人所知。此外，机器制造的孔隙仍然难以分离大小和性质相似的离子（如钠和钾）。因此，在诸如液体在固体表面上的摩擦、增强分子分离的机制以及受限几何中的离子传输及其控制等基本问题上，仍有许多问题有待了解。提出的研究旨在全面了解离子/水分子如何在极端限制下与机器制造的微孔壁相互作用。这将通过研究从这些微小孔隙中流出的微观流动（以流速/离子通量的方式）来实现，同时调整孔隙壁的电导率和电荷。这些研究将为液体在固体表面上的摩擦提供系统的定量实现，为选择合适的通道壁材料以精确控制流体在受限几何形状下的输运提供参考，从而实现生物孔隙等增强的水/离子选择性。在整个研究期间，我还将在基础/设备层面发展基本的理论理解和高级建模，以推进设备原型的实验和优化。在这些发现的基础上，该奖学金将建立(i)用于离子传输的生物电子界面和存储设备的人工流体装置和（ii）用于水净化和从盐浓度梯度中收集能量的膜的制造。从第四年开始，我将与曼彻斯特石墨烯工程创新中心合作，扩大能源和环境应用的流体装置和膜制造，目标是为英国的能源独立做出贡献，到2050年实现温室气体净零排放。为了进一步获得奖学金，我和我的团队将制定实验确定受限几何中的分子排列的方案，以使其对受限流体传输的贡献合理化。因此，该奖学金全面解决了当前纳米流体研究的知识空白，并为在受限流体传输，表面科学和固体物理的界面上建立新的研究方向铺平了道路。所有这些，除了产生高影响力的出版物和专利，使我成长为这个领域的领导者，朝着我在英国建立自然启发的纳米流体研究中心的长期目标前进，以解决世界各地的一些重大挑战（清洁增长；可持续性；水和食物能源）。

The surfaces of the living cells that make up our bodies consist of exquisitely engineered tiny pores of size less than a nanometer (i.e., one ten-thousandth of the diameter of a human hair). Nature has evolved these pores to efficiently harness inter-molecular forces and surface effects for achieving exceptional water/ion selectivity and ion transport even counter to concentration gradients. Therefore, they play a critical role in functioning of human kidneys to remove waste/extra-fluids from the blood and, allow brain-cells (i.e., neurons) to generate electrical pulses required for the brain to sense and compute. For example, concentration gradients driven ion transport across a neuron cell membrane generates electrical signals and transmit them with speeds of tens of meters per second as a means of communication. The proposed research aims at making similar pores inside a laboratory to make (i) artificial fluidic devices that allow direct communication to/from cells in their language (exchanging ions/water molecules), and (ii) membranes for producing energy by mixing fresh water with seawater and energy efficient removal of salt from seawater with minimal production of carbon dioxide.Unlike water flow in a garden hose, the physics of fluidic motion through the pores of nanometer-size is barely understood. Also, machine-made pores still struggle to separate ions (like sodium and potassium) with similar size and properties. Therefore, there remains much to be understood on fundamental issues such as friction of liquids on solid surfaces, mechanisms for enhanced molecular separation, and ionic transport in confined geometries and its control. The proposed research aims at establishing a comprehensive understanding of how ions/water molecules interact with the walls of machine-made tiny pores under extreme confinements. This will be achieved through investigation of microscopic flows (in terms of flow rate/ionic flux) emerging out of such tiny pores while tuning electric conductivity and electric charge of the walls of the pore. These studies will provide a systematic realization of friction for liquids on solid surfaces with quantification, which acts as reference for choosing appropriate channel wall materials for precisely controlling the fluidic transport at confined geometries to achieve enhanced water/ion selectivity like biological pores. Throughout this Fellowship, I will also develop essential theoretical understanding and advanced modelling at fundamental/device level for advancing the experiments and optimization of device-prototyping.Building on these findings, this fellowship will establish the fabrication of (i) artificial fluidic devices for ion-transport based bioelectronic interfaces and memory devices and (ii) membranes for water purification and energy harvesting from salt-concentration gradients. From the fourth year of this Fellowship, I will work with Graphene Engineering Innovation Centre at Manchester to scale up fluidic devices and membrane fabrication for energy and environmental applications with an aim of contributing to the UK's Energy Independence and achieving net zero greenhouse gases emission by 2050.Further to this Fellowship, my team and I will develop schemes for the experimental determination of the molecular arrangement in confined geometries to rationalize its contribution on confined fluidic transport. Therefore, this Fellowship comprehensively addresses knowledge gaps in present-day nanofluidics research and paves path to establish a new direction of research at the interface of confined fluidic transport, surface science and solid-state physics. All this, besides producing high-impact publications and patents, enables me to grow as a leader in this field to progress towards my long-term aim of establishing Nature-Inspired Nanofluidics Research Center in the UK to address a number of Grand Challenges (clean growth; sustainability; water and energy for food) across the world.