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:

Siyang LUO, Graduate student.

Research interest:  Droplet spreading on biofilm

      Traditionally, solid and liquid methods have been defined by measuring the degree of deformation of a substance under the same force, ie, the Young's modulus, but for some complex fluids (eg, non-Newtonian fluids, gels, biomass, etc.) This method of definition no longer applies. In order to define whether the material properties of biofilms are biased toward solid or biased liquids, we attempted to determine the material properties of biofilms by studying the hydrodynamic properties of the biofilm interface, the properties of the droplets spreading on the biofilm. The process is mainly taken by CCD, measuring and plotting R~t images and θ~t images and comparing them with other literature work.

放慢100倍下观察液滴在细菌膜上超快铺展过程（5000帧每秒拍摄）