Conoscopic analysis of electric field driven planar aligned nematic liquid crystal

Abstract

This paper illustrates the conoscopic observation of a molecular reconstruction occurring across a nematic liquid crystal (NLC) medium in the presence of an external electric field. Conoscopy is an optical interferometric method, employed to determine the orientation of an optic axis in uniaxial crystals. Here a planar aligned NLC medium is used, and the topological changes with respect to various applied voltages are monitored simultaneously. Homogenous planar alignment is obtained by providing suitable surface treatments to the ITO coated cell walls. The variation in the conoscopic interferometric patterns clearly demonstrates the transition from planar to homeotropic state through various intermediate states.

Non-newtonian fluids and droplets in microchannels

“…Investigation on behaviors of liquid crystal under external fields has been reported for the past decades, such as electric field [124,[215][216][217], temperature field [200,201,211] and shear flow at normal scale [218]. called calamities which has a rod-like molecular structure [120].…”

“…The rod-like molecular structural become observable illuminated by polarized light as it is in nematic phase. Most of the literatures have been focusing on the its' dynamic behavior under electric field [124,[215][216][217]219]. Very few works have been done to study the reorientation under hydrodynamic pressure gradient at micro scale [212].…”

“…The anchoring condition is primarily determined by the surface property. Various methods were proposed to modify the surface anchoring condition for the microfluidics prevailing PDMS channel.Mechanical treatment and chemical coating are the two major types[123,124].…”