Wave propagation and acoustic band gaps of two-dimensional liquid crystal/solid phononic crystals

Abstract

The vast majority of acoustic wave propagation in phononic band studies has been usually carried out by scattering inclusions embedded in a viscoelastic medium, such as air or water. In this study, we present calculated band structure results for the two-dimensional square array geometry of a solid cylindrical scatterer surrounded by a liquid crystal (LC) matrix. Liquid crystals provide a unique combination of liquidlike and crystal-like properties as well as anisotropic properties. The purpose of using LC material is to take advantage of longitudinal acoustic waves propagating parallel (||) and perpendicular (\) to the nematic liquid crystal (NLC) director n. The compound used in this study was a room temperature NLC, called 5CB (4-pentyl-4 0 -cyanobiphenyl). The acoustic band structure of a two-dimensional phononic crystal containing a 5CB NLC and lithium tantalate was investigated by the plane wave expansion method. The theoretical results show that the solid/LC system can be tuned in a favorable configuration for adjusting or shifting acoustic band gaps.

Narrow Band Solid-Liquid Composite Arrangements: Alternative Solutions for Phononic Crystal-Based Liquid Sensors

“…Since the acoustic properties of these composite arrangements depend on material properties of structure constituents, variation of one material property causes a change in the transmission behavior of the whole structure [17,18,19]. Analyzes of phononic crystals constituting a liquid have been published in [20,21,22,23]. They indicate that a variation of properties of the liquid constituent changes their response in a distinct manner.…”