LPMCN, Université de Lyon, Université Lyon 1 and CNRS, UMR 5586, F-69622 Villeurbanne, France.
Phys Rev Lett. 2010 Aug 20;105(8):088304. doi: 10.1103/PhysRevLett.105.088304. Epub 2010 Aug 17.
In this Letter, we investigate experimentally the nonequilibrium steady state of an active colloidal suspension under gravity field. The active particles are made of chemically powered colloids, showing self propulsion in the presence of an added fuel, here hydrogen peroxide. The active suspension is studied in a dedicated microfluidic device, made of permeable gel microstructures. Both the microdynamics of individual colloids and the global stationary state of the suspension under gravity are measured with optical microscopy. This yields a direct measurement of the effective temperature of the active system as a function of the particle activity, on the basis of the fluctuation-dissipation relationship. Our work is a first step in the experimental exploration of the out-of-equilibrium properties of active colloidal systems.
在这封信件中，我们通过实验研究了重力场下活性胶体悬浮液的非平衡稳态。活性粒子由化学动力胶体组成，在添加燃料（这里是过氧化氢）的情况下表现出自推进。活性悬浮液在专门的微流控装置中进行研究，该装置由可渗透的凝胶微结构组成。通过光学显微镜测量单个胶体的微动力学和重力下悬浮液的全局稳定状态。这基于涨落耗散关系，直接测量了活性系统的有效温度作为粒子活性的函数。我们的工作是实验探索活性胶体系统非平衡特性的第一步。
