20 May 2021 (Thu)

3:30 – 4:30 pm (HK Time)

Join on Zoom (the meeting link will be sent to successful registrants)
Remarks: e-Certificate of attendance will be provided. Latecomer or early leaver of the webinar might NOT be eligible for an attendance certificate.

Guest Speaker: Dr Zhang Rui

Assistant Professor
Department of Physics
The Hong Kong University of Science and Technology

Dr ZHANG Rui is currently an Assistant Professor of Department of Physics at HKUST. Before joining HKUST, he was a Distinguished Research Associate in the Pritzker School of Engineering at the University of Chicago. Prior to that, he was at the Levich Institute for Physico-Chemical Hydrodynamics at City College of New York. He obtained his B.S. in Physics from Fudan University. Dr Zhang is a computational soft matter physicist specialized in active matter, liquid crystals and nanofluidics. He has published in many top journals, including Nature Materials, PNAS, Nature Communications, Science Advances and others.

Active Matter Meets Liquid Crystals: Searching for Building Blocks of Autonomous Materials


Active matter encompasses a wide spectrum of non-equilibrium systems, the constituents of which can convert energy into local mechanical work, and give rise to long-range collective dynamics. Examples include flocking birds, fish school and spontaneous flows in cytoplasm. In many active matter systems, their constituent particles are of anisotropic shape and often-times densely packed, rendering them in an active liquid crystal (LC) phase. In recent years, active LCs have been discovered in a variety of biological systems and also realized in lab. This new class of materials is on the one hand sensitive to external fields, a feature inherited from LCs, and on the other hand active in that it can engender spontaneous motions and flows. We therefore envision its future application as a building block for autonomous materials.

In this talk, I will discuss our recent efforts in understanding and manipulating active nematic LCs in terms of their microstrutures. Specifically, I will show you that our hydrodynamic model can be harnessed to predict the morphology and dynamics of topological defects in actin-based nematic. I will further demonstrate that through activity patterning, the nucleation and self-propulsion dynamics of defects can be well controlled. Our predictions have been confirmed in actin-myosin-based experiments performed by our collaborators. I will conclude by showing that it is possible to perform logic operations through topological defects, paving the way towards building LC-based autonomous materials.