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。这种微器件通常集成在多功能单元中，不仅提供了比传统大规模技术更多的优势，而且在许多不同的研究领域提供了多种潜在的用途，这些研究领域开发了受限几何中的流体。它们有许多实际应用，包括药物输送(如吸入器、微针)、分析设备、护理点诊断、连续流动、小规模集约化制造、制药研究、临床和兽医诊断等。在微通道设备中，流体在受限几何形状中流动，尽管已经取得了重大进展，但仍然缺乏对从分子尺度到宏观流体动力学过程等广泛长度尺度上发生的不同现象以及它们如何相互关联的了解。更具体地说，拟议的研究侧重于微结构，如膜、微接触器或图案化衬底，如何影响微空间中多相流的流体力学和热力学；更重要的是，微结构的存在如何影响它们。这种认识对于进一步发展微流控器件的应用及其在强化热质传递方面的应用是至关重要的。从基础研究和应用研究的角度来看，微工程器件的研究都面临着许多挑战。我们认为，对这类装置进行全面和系统的研究应该涉及跨学科的方法，需要使用不同领域的工具和制定新的方法。这项提议寻求为一项全面的四年研究方案提供资金，使其成为一种新的协同方法，该方法将结合最先进的实验技术、复杂的计算流体力学和分子建模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/热力学和流体力学水平上合理地理解和定量描述微结构受限几何中的流体过程，从而建立在相距很远的尺度上发生的现象之间的联系。作为一个主要的案例，我们将考虑微尺度流体分离，它突出了微工程技术中目前尚未解决的一些关键问题，即受限几何中的汽液平衡和突破过程(即一相侵入另一相)。我们的主要发现还将用于探索微观结构发挥核心作用的其他应用，如微蒸馏、滑移流和液滴形成。这项工作将由伦敦帝国理工学院化工系的一个团队承担，他们的技能和优势互补：Kalliadsis(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工系的一个团队：Gavriilidis(实验微型化学工程和微流体)、Kuhn(微流体、多相流模拟和实验)和Sorensen(过程设计、蒸馏微)。

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).