Name of Research Group:Soft Matter Physics Lab (SMPL)

Description of Research Group:Our research interests are the classical topics in the soft matter physics, including the wetting phenomena, the passive and active Brownian motion in confined space and the self-assembly away from equilibrium state.

Colloidal particles in the Hele-Shaw cell exhibit distinct dynamics due to the confinement. The interaction among the particles make the problem much complicated. The microscopic collision process between particles and the thinning fluid layer surrounded is intriguing in the confined 2D system. By using the thermal controlling, magnetic (electric) filed we play the games on the Brownian motion of the passive particles and active stochastic microswimmers.

Recently, we are employing the bacteria, E. Coli, to illustrate the hydrodynamic behavior in the microfluidic channels, and the run-tumble active random motion. We quantitatively measure the bacteria orientation responding to the surrounding fluid flow, especially when the mean velocity of the fluid is comparable with the swimming velocity of the bacteria. We are extremely attracted to the collective motion, active rheology of the bacteria in the limited slow Poisseuille flow in the microfluidic channels.

Meanwile, drying suspension on diverse substrates with varying conditions is another topic we are still working on. Wetting control by nanostructured semiconductor materials is dedicated to the drying pattern from the colloidal suspension. Pressure (high pressure/vacuum) and temperature (heating and frozen) are used to control the drying dynamics of drops with the complex fluid.

Team members Introduction:

郑欢

研究兴趣：自驱动粒子的二维主动扩散与迁移

        隐藏在我们视线之外，存在大量微小粒子、微生物的运动，而大多数情况下，这些运动发生在一个有界的空间环境中，因此，边界的出现是不可避免的。这些粒子的运动可以是被动的，主要是无所不在的热运动（布朗运动），也可以是主动运动，包括细菌生存需要所必须的游泳运动，生命过程的进行所必须的细胞迁移等生命运动。一种常见的场景是粒子在二维边界面上的运动，界面上粒子的运动形式规律、机制，以及主动粒子采用何种运动策略则是非常重要的科学问题，理解与阐明这些规律与机制，可为可控粒子运动与调控生命体运动提供重要依据，具有广泛的应用价值。

       在实验上可以通过二维运动中粒子的轨迹信息，演绎许多丰富的物理机理与规律的探索。在获取运动轨迹后，从运动学上说，边提供了速度，即主动粒子的运动能力，动能信息，同时可以提供加速度物理量，进而可以关联相互作用力的动力学方程，从而可以理解各种相互作用力驱动下的动力学机制，并可关联主动粒子的自身反馈与可能的生物习性与生命功能过程。