Species Transport via Ping-Pong Droplets

该项目旨在研究溶解/悬浮物通过瞬态液体孔隙的运输。瞬态孔隙是当液滴在电场的驱动下遇到含水储层时形成的。当电场强度足够大时，形成直径为亚微米的液孔，即连接液滴与储层的液桥。在那之后，液滴反弹回来。将考虑三类溶解/悬浮物质：小分子、纳米粒子和聚电解质。液滴和物种动力学将使用高速视频显微镜和荧光显微镜进行研究。重点将放在液体孔隙作为瞬态筛子的作用上。在此背景下，首先将研究液体孔隙的时空演化。一个重要的目标是确定和理解溶解/悬浮物质通过液体孔隙的主要机制。将检查主要控制参数（例如电压和油相粘度）的影响，目的是在参数空间中确定特别有利于物种分离的区域。在这种情况下，在多大程度上可以控制孔隙的寿命和直径将被特别研究。当孔隙的寿命与溶解/悬浮物质的特征时间尺度相同时，例如小分子的扩散时间或聚电解质的弛豫时间，预计会发现特别有利的物质分离机制。其中许多任务将与子项目B2和B4密切合作执行。预计瞬态效应的探索将为目前主要基于准静止液孔的液体浇注技术提供一个非常有前途的新视角。

The project aims at studying the transport of dissolved/suspended species through transient liquid pores. The transient pores are formed when an aqueous droplet meets an aqueous reservoir, driven by an electric field. For large enough values of the electric field strength, a submicron-diameter liquid pore is formed, i.e. a liquid bridge connecting the droplet and the reservoir. After that, the droplet bounces back. Three classes of dissolved/suspended species will be considered: small molecules, nanoparticles and polyelectrolytes. The droplet and species dynamics will be studied using high-speed videomicroscopy and fluorescence microscopy. The focus will be on the role of the liquid pores as transient sieves. In that context, first the spatio-temporal evolution of the liquid pores will be investigated. One important goal is to identify and understand the main mechanisms of passage of the dissolved/suspended species through the liquid pores. The influence of the main control parameters (for example the voltage and the viscosity of the oil phase) will be examined, with the aim to identify especially favorable regions in the parameter space for species separation. In this context, to what extent the lifetime and diameter of the pore can be controlled will be especially studied. It is expected that particularly favorable regimes for species separation are found when the lifetime of the pore is of the same order of magnitude as characteristic timescales of the dissolved/suspended species, for example the diffusion time of small molecules of the relaxation time of polyelectrolytes. Many of these tasks will be performed in close collaboration with subprojects B2 and B4. It is expected that the exploration of transient effects will add a very promising new perspective to liquid gating technology, which so far is mainly based on quasi-stationary liquid pores.