Capillary rise of active matter

我们研究了细管中活性物质在重力作用下上升的能力和其他相关现象，如垂直板的润湿和自发吸胀，其中润湿液体被吸入多孔介质。这种毛细作用或毛细作用在经典流体中是众所周知的，它源于液体分子与容器壁之间的相互吸引作用，以及液体分子之间的相互吸引。最近，我们在纯排斥相互作用的标量活性物质最小模型中观察到毛细现象，其中由于活性粒子之间以及活性粒子与壁面之间的碰撞减速而产生有效的吸引力。基于这一观察结果，我们将在本项目中回答三个问题：相对于所考虑的活性物质系统的微观细节，活性晶格气体模型预测的毛细上升有多强大？当有吸引力的粒子-壁面相互作用不存在时，活性物质系统中毛细血管上升的机制是什么？在多大程度上，静止的粒子流是造成这种现象的原因？是否有实验实现了活性物质的毛细管上升，例如通过使用活性胶体和我们与里昂小组合作的实验装置，如果有，潜在的机制是什么？

We study the capacity of active matter to rise in thin tubes against gravity and other related phenomena like wetting of vertical plates and spontaneous imbibition, where a wetting liquid is drawn into a porous medium. This capillary action or capillarity is well known in classical fluids and originates from attractive interactions between the liquid molecules and the container walls, and from the attraction of the liquid molecules among each other. Recently, we observed capillarity in a minimal model for scalar active matter with purely repulsive interactions, where an effective attraction emerges due to slowdown during collisions between active particles and between active particles and walls. Based on this observation we will answer three questions in this project: How robust is the capillary rise predicted by an active lattice gas model with respect to microscopic details of the considered active matter system? What is the mechanism behind the capillary rise in active matter system when attractive particle-wall interactions are absent and in how far are stationary particle currents responsible for it? Are there experimental realizations of the precited capillary rise of active matter, for instance by using active colloids and the experimental setup of the Lyon group, with whom we collaborate, and if yes, what are the underlying mechanisms.