Chemically-induced phoretic flow, or how to turn a curtain of light into virtual micro-fluidic boundaries

通过这个项目，我们想要建立和合理化一种独特的方法来操纵水溶液中界面上的胶体颗粒。从表面上看，人们可以考虑光驱动扩散渗透的概念和局部(多孔颗粒)--创造几乎任意流动模式的全局(光强模式)--作为虚拟微流体的实现--即，胶体可以在没有外部泵或微流体室和通道的实壁存在的情况下被运输、限制和操纵。理论分析将使我们深入描述禁闭力的性质，以及它们是否以及如何被表示为有效的溶质势。当热运动和胶体颗粒布朗扩散很重要时，这一点尤其重要。在拟议的研究中，我们打算建立参考实验，其结果可以直接与理论计算和模拟进行比较。除了这些基本问题外，整个现象学还开辟了许多其他“理论相容”的问题，如粒子混合物中的分离动力学或自推进粒子在动态波动的受限几何中的运动，所有这些都可以在本研究期间进行更密切的研究。总而言之，我们的项目提供了关于一个有趣的非平衡系统的理论和实验的异常紧密的结合，该系统在一个独特的环境中触及了许多由磷驱动的粒子动力学以及流体动力学相互作用的前沿问题。

With this project we would like to establish and rationalize an unique way for the manipulation of colloidal particles at interfaces in aqueous solution. Superficially, one may consider the concept of light-driven diffusioosmosis and the local (porous particles)-global (light intensity patterns) ansatz of creating almost arbitrary flow patterns as an implementation of virtual microfluidics – that is, colloids can be transported, confined and manipulated without external pumps or the presence of solid walls of microfluidic chambers and channels. The theoretical analysis will give us an in-depth characterization of the nature of the confining forces, and whether and how they may be represented as an effective solute potential. This is particularly important when thermal motion and colloidal particle Brownian diffusion are important. In the proposed research we intend to set up reference experiments whose results can be compared directly to the theoretical calculations and simulations. In addition to these fundamental questions, the whole phenomenology opens up a number of other “theory-compatible” questions, such as segregation dynamics in mixtures of particles or the motion of self-propelled particles in dynamically fluctuating confined geometries, all of which may be studied more closely during this research. In summary, our project offers an unusually close alignment of theory and experiment regarding an intriguing non-equilibrium system that touches upon many cutting-edge problems of phoretically-driven particle dynamics together with hydrodynamic interactions in a unique setting.