Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom.
Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005, Paris, France.
Nat Commun. 2022 Aug 15;13(1):4776. doi: 10.1038/s41467-022-32520-9.
Understanding the out-of-equilibrium properties of noisy microscale systems and the extent to which they can be modulated externally, is a crucial scientific and technological challenge. It holds the promise to unlock disruptive new technologies ranging from targeted delivery of chemicals within the body to directed assembly of new materials. Here we focus on how active matter can be harnessed to transport passive microscopic systems in a statistically predictable way. Using a minimal active-passive system of weakly Brownian particles and swimming microalgae, we show that spatial confinement leads to a complex non-monotonic steady-state distribution of colloids, with a pronounced peak at the boundary. The particles' emergent active dynamics is well captured by a space-dependent Poisson process resulting from the space-dependent motion of the algae. Based on our findings, we then realise experimentally the de-mixing of the active-passive suspension, opening the way for manipulating colloidal objects via controlled activity fields.
理解嘈杂的微观系统的非平衡特性以及它们在多大程度上可以外部调制，是一个至关重要的科学和技术挑战。它有望解锁从在体内靶向输送化学物质到定向组装新材料等颠覆性新技术。在这里，我们专注于如何利用活性物质以统计上可预测的方式运输被动微观系统。使用弱布朗粒子和游动微藻的最小主动-被动系统，我们表明空间限制导致胶体的复杂非单调稳态分布，在边界处出现明显的峰值。粒子的突现主动动力学很好地被藻类空间依赖性运动引起的空间依赖性泊松过程所捕获。基于我们的发现，我们随后通过实验实现了主动-被动悬浮液的去混合，为通过受控活性场操纵胶体物体开辟了道路。
