Session Overview |
Photonics materials - Bloc 2Room: International 2 |
Date: Thursday, June 07 |
13:00 |
Motile Bacteria at Interfaces of Liquid Crystals
Main Author: Nicholas Abbott Organization: University of Wisconsin-Madison, United States Bacteria often inhabit and exhibit distinct dynamical behaviors at interfaces, but the physical mechanisms by which interfaces cue bacteria are still poorly understood. This presentation will describe studies of motile bacteria at the interfaces of both lyotropic and thermotropic liquid crystals (LCs). |
13:25 |
Using liquid crystals to study the behavior of motile bacteria and vice versa
Main Author: Simon Rainville Organization: Université Laval, Canada The water solubility of lyotropic liquid crystals (LCs) makes them very attractive to study the behavior of biological microorganisms in an environment where local symmetry is broken. Several recent studies have shown a dramatic change in the behavior of flagellated bacteria when swimming in solutions of the lyotropic LC disodium cromoglycate (DSCG): instead of performing a random walk in 3D, the bacteria move along linear trajectories. Our understanding of this phenomenon was improved by observing the movements of Escherichia coli bacteria swimming in DSCG-water solutions of different concentrations. In addition, the viscosity of DSCG aqueous solutions was measured as a function of concentration at room temperature. Interestingly, these observations enabled us to identify a previously undescribed isotropic pretransition zone where bacteria start sticking to each other and to surfaces. Simple estimations show that the unbalanced osmotic pressure induced depletion force might be responsible for this sticking phenomenon. Finally, by visualizing the filaments while the cell reverses its swimming direction, we were led to propose that the flagellum’s hook might temporarily “lock-up” for the motor’s rotation to flip it from one side of the cell to the other. |
13:50 |
Light-Driven Motions of Liquid Crystal Polymers
Main Author: Yue Zhao Organization: Université de Sherbrooke, Canada New liquid crystal polymers are developed to perform macroscopic motions guided by laser. The results show the perspective of miniature soft robots controlled by an external light source. |
14:15 |
Liquid crystal devices for optical shutter technology
Main Author: Ethan Jull Organization: University of Leeds, United Kingdom Liquid crystal materials have been utilised exceptionally well in modern technology, especially in the field of displays. However, as display technologies become mature, investigations into novel liquid crystal phases, material combinations, and device configurations are leading to developments of many interesting non-display applications. Here we present our research surrounding the use of liquid crystal materials for rapid response time, high optical density, and automatic all-optical switchable shutters. |
14:40 |
Optical phase properties of a large diameter liquid crystal lens
Main Author: Marenori Kawamura Organization: Akita University, Japan We propose a liquid crystal (LC) lens with Fresnel–type optical phase retardations for enlarging an effective lens diameter. The LC lens consists of multiple ring electrodes and a circular electrode inside coated with circular highly resistive films divided into three parts. Almost circular interference fringes can be smoothly tuned by adjusting the voltage applied across each ring electrode and a common electrode, and the Fresnel–type optical phase retardation can be obtained. |