Light-controlled transient barriers

光控瞬态屏障

• 批准号: 530216682
• 负责人: Professorin Dr. Regine von Klitzing
• 金额: --
• 依托单位: Arbeitsgruppe Weiche Materie an Grenzflächen
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/530216682?language=en
• 关键词: Light; controlled; transient; barriers

In agreement with the overarching goal of the Research Unit TRANSIEVES we will design a light-controlled transient sieve for particles. Light-controlled transient sieves are expected to be switched on and off quite quickly and easily adapted to a desired purpose by simply changing the light intensity profile. The overarching goal of the subproject A2 is, in collaboration with B1, to design, realize and optimize a transient sieve based on light sensitive microswimmers in a transient light gradient. In this subproject the swimmers are thermophoretic Janus particles with a gold cap which converts light energy into heat. They are prepared and partially characterized together with subproject A5. The heat at the gold cap leads to a temperature gradient, which leads to an osmotic flow of the surrounding solvent along the surface of the Janus particle and a movement of the Janus particle opposite to the flow (momentum conservation). We plan to use a spatiotemporally modulated light field to create a transient sieve which can be easily opened and closed in a controlled and rapid manner. The particles can pass through or will be blocked by the sieve, depending on their properties such as size, surface morphology or charge. One of the main questions is how the dynamics of the self-propelled Janus particles relate to the dynamics of the temporally modulated light field to achieve an efficient sieve performance. Therefore, first, fundamentals of the propulsion of thermophoretic swimmers in a static light gradient have to be explored. For example, it needs to be clarified which particle parameters are responsible for a pronounced difference in velocity and direction of the particles in the light gradient. Experimental parameters such as light gradient and width of the gradient, as well as a suitable temporal modulation of the light field will be adjusted according to the results of subproject B1 to test the theory. Therefore, our existing set-up for tracking particles will be upgraded with a combination of an electrooptical modulator and a rotating mirror allowing to tailor the light field. The hypothesis is that the characteristic opening time of the sieve for optimal sieving performance is related to the diffusional rotation time of the Janus particles. Details will be analysed in B4. Furthermore, the outcome of subproject B1 will be used to create design rules for an efficient performance of the transient sieve. In a later period of the subproject, a microgel will be attached to the Janus particle as cargo, which can have different functions, such as changing the fluid dynamics around the particle, and/or acting as a stimuli sensitive container for smaller molecules, which can be carried inside the microgel across the barrier and released behind the transient barrier.

在协议的总体目标的研究单位过渡，我们将设计一个光控瞬态粒子筛。预期光控瞬态筛通过简单地改变光强度分布而相当快速地打开和关闭并且容易地适应于期望的目的。子项目A2的总体目标是与B1合作，设计、实现和优化基于瞬态光梯度中的光敏微泳者的瞬态筛。在这个子项目中，游泳者是具有将光能转化为热量的金帽的热泳Janus粒子。它们是与次级项目A5一起编写和部分说明的。金帽处的热量导致温度梯度，这导致周围溶剂沿着Janus粒子表面的渗透流以及Janus粒子与流动相反的运动（动量守恒）。我们计划使用时空调制光场来创建一个瞬态筛，它可以很容易地打开和关闭在一个控制和快速的方式。颗粒可以通过或将被筛子阻挡，这取决于它们的性质，例如尺寸、表面形态或电荷。其中一个主要问题是自推进Janus粒子的动力学如何与时间调制光场的动力学相关，以实现有效的筛分性能。因此，首先，必须探索在静态光梯度中热泳游泳者推进的基本原理。例如，需要澄清哪些粒子参数负责光梯度中粒子的速度和方向的显著差异。将根据子项目B1的结果调整实验参数，如光梯度和梯度宽度，以及适当的光场时间调制，以检验理论。因此，我们现有的跟踪粒子的设置将通过光电调制器和旋转镜的组合进行升级，从而可以定制光场。该假设是，用于最佳筛分性能的筛的特征打开时间与Janus颗粒的扩散旋转时间有关。详情将在B4中分析。此外，子项目B1的成果将用于制定瞬态筛有效性能的设计规则。在该子项目的后期，微凝胶将作为货物附着在Janus粒子上，其可以具有不同的功能，例如改变粒子周围的流体动力学，和/或作为较小分子的刺激敏感容器，其可以在微凝胶内穿过屏障并在瞬态屏障后面释放。