Past Seminars Seminários Já Decorridos 2013

Necklaces of Liquid Crystal Beads

By: Yong Geng
From: Universidade Nova de Lisboa
At: Instituto de Investigação Interdisciplinar, Anfiteatro
[2013-04-11] 11:30

Liquid crystal droplets dispersed in a continuous matrix have important applications in electro-optical devices [1]. They also produce intriguing topological defect structures due to the confinement of the liquid crystal by closed boundaries that impose alignment at the interface.
In this work we use a simple method to generate stable liquid crystal droplets topologically equivalent to a toroid by depositing tiny volumes of a liquid crystals (nematic and cholesteric) on cellulosic micro-fibers (1 μm diameter) suspended in air.
This system can exhibit different structures depending on the liquid crystal types, droplet size, anchoring condition, and also external stimuli like temperature and electric field. The necklaces of such liquid crystal drops constitute excellent systems for fundamental studies and open new perspectives for applications [2], such as tunable photonic and waveguide applications.

[1] M. Humar, M. Ravnik, S. Pajk, M. Musevic, S. Pajk and I. Musevic, Nat. Photonics, 3, 595–600 (2009).
[2] Y. Geng, P. L. Almeida, J. L. Figueirinhas, E. M. Terentjevd and M. H. Godinho,  Soft Matter (2012).