Fluid processes in smart microengineered devices: Hydrodynamics and thermodynamics in microspace

目前的微流控设备市场规模为20亿美元，预计到2016年将翻一番。这种微型装置通常集成在多功能单元中，这不仅比传统的大型技术具有许多优势，而且在许多不同的研究领域中提供了许多潜在的用途，这些研究领域利用了受限几何形状的流体。它们有许多实际应用，包括药物输送（例如吸入器、微针）、分析设备、护理点诊断、连续流小规模强化生产、药物研究、临床和兽医诊断等。在微通道设备中，流体在受限的几何形状中流动，尽管已经取得了重大进展，但了解从分子尺度过程到宏观流体动力学过程的各种长度尺度上发生的不同现象，以及它们之间的相互关系，仍然缺乏。更具体地说，提出的研究重点是微观结构，如膜，微接触器或图案衬底，如何影响微空间中多相流的流体动力学和热力学；更重要的是它们是如何受到微观结构的影响的。这种理解对于进一步推进微流体装置的应用及其在热质输运方面的应用是至关重要的。在微观结构存在的情况下，微工程器件的研究无论从基础研究还是应用研究的角度来看都面临着许多挑战。我们认为，对这类装置进行全面和系统的研究应该涉及一种跨学科的方法，这种方法需要使用来自不同领域的工具和开发新的方法。该提案寻求资助一项为期四年的综合研究计划，研究一种新的协同方法，该方法将结合最先进的实验技术、复杂的计算流体动力学和分子模型以及以前从未尝试过的先进理论物理元素。我们的目标是在分子/热力学和流体动力学水平上合理理解和定量表征微观结构受限几何中的流体过程，从而建立在广泛分离尺度上发生的现象之间的联系。作为一个主要的案例研究，我们将考虑微尺度流体分离，它突出了微工程技术中一些目前尚未解决的关键问题，即受限几何中的气液平衡和突破过程（即一个相侵入另一个相）。我们的主要发现也将用于探索微结构发挥核心作用的其他应用，例如微蒸馏，或滑动流动和液滴形成。这项工作将由伦敦帝国理工学院化学工程系的一个团队承担，他们具有互补的技能和优势：Kalliadasis（流体力学/统计力学-计算，理论），Galindo（统计力学/分子动力学-计算）和Pradas（统计/理论物理-计算，理论）；以及来自伦敦大学学院化学工程系的一个团队：Gavriilidis（实验微化学工程和微流体），Kuhn（微流体，多相流建模和实验）和Sorensen（工艺设计，微蒸馏）。

The current microfluidic devices market is $2 Billion and expected to double by 2016. Such microdevices are usually integrated in multifunctional units, which not only offer numerous advantages over traditional large-scale technologies, but also provide a multitude of potential uses in many different research fields that exploit fluids in confined geometries. They have numerous practical applications including drug delivery (e.g. inhalers, microneedles), analytical devices, point of care diagnostics, continuous flow small scale intensified manufacturing, pharmaceutical research, clinical and veterinary diagnostics, etc. In microchannel devices fluids flow in confined geometries and although significant progress has been made, understanding how the different phenomena occurring across a wide range of lengths scales, from molecular-scale processes to macroscopic hydrodynamic ones, and how they are related to each other, is still lacking. More specifically, the proposed research focuses on how microstructures, e.g. membranes, microcontactors, or patterned substrates, affect the hydrodynamics and thermodynamics of multiphase flows in microspace; and more importantly how they are influenced by the presence of the microstructure. Such understanding is critical for furthering the applications of microfluidic devices and their utilisation for heat-mass transport enhancement.The study of microengineered devices in the presence of microstructure posseses many challenges from both a fundamental and applied research point of view. It is our belief that a complete and systematic study of such devices should involve an interdisciplinary approach that requires the use of tools and the development of new methodologies from different areas. This proposal seeks funding for a comprehensive four-year research programme into a novel synergistic approach that will combine state-of-the-art experimental techniques, sophisticated computational fluid dynamics and molecular modeling as well as advanced theoretical physics elements, never attempted before. We aim at rationally understanding, and quantitatively characterising fluid processes in microstructured confined geometries, on both the molecular/thermodynamic and hydrodynamic level, hence establishing connections between phenomena occurring at widely separated scales. As a main case study we shall consider microscale fluid separation which highlights some of the currently unresolved, yet key issues in microengineering technology, namely vapour-liquid equilibrium in confined geometries and breakthrough process (i.e. one phase invading into another). Our main findings will also be used to explore other applications where microstructures play a central role, such as microdistillation, or slip flows and droplet formation. The work will be undertaken by a team from the Chemical Engineering Department at Imperial College London with complementary skills and strengths: Kalliadasis (Hydrodynamics/Statistical Mechanics -- Computations, Theory), Galindo (Statistical Mechanics/Molecular Dynamics -- Computations), and Pradas (Statistical/Theoretical Physics -- Computations, Theory); and a team from the Chemical Engineering Department at University College London: Gavriilidis (Experimental Microchemical Engineering and Microfluidics), Kuhn (Microfluidics, Multiphase Flows Modelling and Experiments), and Sorensen (Process Design, Microdistillation).