Species Transport via Ping-Pong Droplets

该项目旨在研究溶解/悬浮物质通过瞬时液体孔隙的迁移。当水性液滴遇到水性储层时，在电场的驱动下形成瞬时孔。对于足够大的电场强度值，形成亚微米直径的液体孔，即连接液滴和储器的液体桥。在那之后，液滴反弹回来。将考虑三类溶解/悬浮物质：小分子、纳米颗粒和聚电解质。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。重点将放在作为瞬态筛的液体孔隙的作用。在这种情况下，首先将研究液体孔隙的时空演化。一个重要的目标是识别和理解溶解/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，电压和油相的粘度）的影响，目的是在参数空间中识别对于物质分离特别有利的区域。在这种情况下，在何种程度上可以控制的寿命和孔径将特别研究。预计当孔的寿命与溶解/悬浮物质的特征时间尺度（例如聚电解质的弛豫时间的小分子的扩散时间）具有相同的数量级时，发现用于物质分离的特别有利的制度。其中许多任务将与次级项目B2和B4密切合作执行。可以预见，对瞬态效应的探索将为目前主要基于准静态液孔的液态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.