Suppression of defects in liquid crystal filled polymer structures using materials exhibiting a frequency dependent dielectric anisotropy inversion

2021 ◽  
Author(s):  
Garry Lester ◽  
Adrian M. Strudwick
Keyword(s):  
Liquid Crystal ◽  
Dielectric Anisotropy ◽  
Frequency Dependent ◽  
Filled Polymer

scholarly journals Signal Amplification in an Optical and Dielectric Biosensor Employing Liquid Crystal-Photopolymer Composite as the Sensing Medium

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 81
Author(s):  
Hassanein Shaban ◽  
Shih-Chun Yen ◽  
Mon-Juan Lee ◽  
Wei Lee
Keyword(s):  
Dielectric Constant ◽  
Liquid Crystal ◽  
Uv Irradiation ◽  
Signal Amplification ◽  
Limit Of Detection ◽  
Optical Signal ◽  
Uv Exposure ◽  
Dielectric Anisotropy ◽  
Optical Texture ◽  
Potential Development

An optical and dielectric biosensor based on a liquid crystal (LC)–photopolymer composite was established in this study for the detection and quantitation of bovine serum albumin (BSA). When the nematic LC E7 was doped with 4-wt.% NOA65, a photo-curable prepolymer, and photopolymerized by UV irradiation at 20 mW/cm2 for 300 s, the limit of detection determined by image analysis of the LC optical texture and dielectric spectroscopic measurements was 3400 and 88 pg/mL for BSA, respectively, which were lower than those detected with E7 alone (10 μg/mL BSA). The photopolymerized NOA65, but not the prepolymer prior to UV exposure, contributed to the enhanced optical signal, and UV irradiation of pristine E7 in the absence of NOA65 had no effect on the optical texture. The effective tilt angle θ, calculated from the real-part dielectric constant ε’, decreased with increasing BSA concentration, providing strong evidence for the correlation of photopolymerized NOA65 to the intensified disruption in the vertically oriented LC molecules to enhance the optical and dielectric signals of BSA. The optical and dielectric anisotropy of LCs and the photo-curable dopant facilitate novel quantitative and signal amplification approaches to potential development of LC-based biosensors.

scholarly journals Effect of Doping ofCd1−xZnxS/ZnS Core/Shell Quantum Dots in Negative Dielectric Anisotropy Nematic Liquid Crystal p-Methoxybenzylidene p-Decylaniline

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 605
Author(s):  
Ayushi Rastogi ◽  
Fanindra Pandey ◽  
Rajiv Manohar ◽  
Shri Singh
Keyword(s):  
Quantum Dots ◽  
Liquid Crystal ◽  
Dielectric Permittivity ◽  
Nematic Liquid Crystal ◽  
Phase Shifters ◽  
Ion Trapping ◽  
Dielectric Anisotropy ◽  
Core Shell ◽  
Optical Parameters ◽  
Dielectric Parameters

We report the effect of the doping of Cd1−xZnxS/ZnS core/shell quantum dots (CSQDs) in nematic liquid crystal p-methoxybenzylidenep-decylaniline (MBDA) at 0.05 wt/wt%, 0.1 wt/wt%, 0.15 wt/wt%, 0.2 wt/wt%, 0.25 wt/wt%, and 0.3 wt/wt% concentrations of CSQDs in MBDA. Dielectric parameters with and without bias with respect to frequency have been investigated. The change in electro-optical parameters with temperature has also been demonstrated. The increase in the mean dielectric permittivity was found due to the large dipole moment of CSQDs, which impose stronger interactions with the liquid crystal molecules. The dielectric anisotropy changes sign on doping CSQDs in MBDA liquid crystal. It was concluded that the CSQD doping noticeably increased the dielectric permittivity of nematic MBDA in the presence of an electric field. The doping of CSQDs in nematic MBDA liquid crystal reduced the ion screening effect effectively. This phenomenon is attributed to the competition between the generated ionic impurities during the assembling process and the ion trapping effect of the CSQDs. The rotational viscosity of nematic liquid crystal decreased with increasing concentration of the CSQDs, with a faster response time observed for the 0.05 wt/wt% concentration. The birefringence of the doped system increased with the inclusion of CSQDs in MBDA. These results find application in the field of display devices, phase shifters, LC – gratings, TIR waveguide, industries, and projectors.

66.1: High Birefringence and Negative Dielectric Anisotropy Liquid Crystal Mixtures for Vertical Alignment Applications

2009 ◽  
Vol 40 (1) ◽  
pp. 992
Author(s):  
Sebastian Gauza ◽  
Meizi Jiao ◽  
Shin-Tson Wu ◽  
Przemysław Kula ◽  
Roman Dabrowski ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Dielectric Anisotropy ◽  
Vertical Alignment ◽  
High Birefringence

scholarly journals Installation for measuring the dielectric anisotropy of liquid crystals at low frequencies by the bridge method with constant displacement

2021 ◽  
Vol 1198 (1) ◽  
pp. 012006
Author(s):  
S V Kalashnikov ◽  
N A Romanov ◽  
A V Nomoev
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Internal Resistance ◽  
Dielectric Anisotropy ◽  
Dielectric Parameters ◽  
Low Frequencies ◽  
Offset Voltage ◽  
Wide Range ◽  
Ac Current ◽  
Constant Displacement

Abstract Installation designed to measure the dielectric anisotropy in laboratory studies of liquid crystal polymer films is described. The installation operates on the principle of a balanced alternating current (AC) bridge, allowing the application of a direct external current (bias) to the liquid crystal cell. The internal resistance of the direct current (DC) source, which affects the equilibrium condition of the bridge, is compensated. The frequency of the AC current feeding the bridge and the offset voltage of the cell is regulated within a wide range, which makes it possible to study various functional dependences of the dielectric parameters of liquid crystals and their modifiers.Introduction

Electro-optic characteristics of the fringe in-plane switching liquid crystal device for a liquid crystal with negative dielectric anisotropy

2013 ◽  
Vol 40 (3) ◽  
pp. 368-373 ◽  
Author(s):  
Mi Hyeon Jo ◽  
Hong Jun Yun ◽  
In Won Jang ◽  
Il Hwa Jeong ◽  
Seung Hee Lee ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Dielectric Anisotropy ◽  
Liquid Crystal Device ◽  
Electro Optic

Mesomorphic, dielectric, and optical properties of fluorosubstituted biphenyls, terphenyls, and quaterphenyls

2008 ◽  
Vol 16 (4) ◽  
Author(s):  
P. Kula ◽  
A. Spadło ◽  
J. Dziaduszek ◽  
M. Filipowicz ◽  
R. Dąbrowski ◽  
...  
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Dielectric Anisotropy ◽  
Polar Group ◽  
The Novel ◽  
Vertical Alignment ◽  
Rigid Core ◽  
High Birefringence ◽  
Low Viscosity ◽  
Dielectric And Optical Properties

AbstractCompounds with moderate and large negative dielectric anisotropy (Δɛ) are very attractive liquid crystal (LC) for vertical alignment mode (VA). Materials with such properties can be achieved by lateral substitution of a polar group into a mesogenic molecule. We synthesized some new LC materials with a negative value of Δɛ, a moderately high birefringence (Δn), and a low viscosity. The mesomorphic and physical behaviour of the novel biphenyls, terphenyls and quaterphenyls fluorosubstituted in the rigid core and also with fluorinated alkyl and alkoxy chains are investigated. The prepared series of four LC compounds are promising for new LC mixtures for various applications. Examples of nematic mixtures with Δɛ∼−3.25 will be presented.

Influence of the frequency of external applied voltage on the dielectric anisotropy of liquid crystal

2018 ◽  
Vol 33 (3) ◽  
pp. 175-181
Author(s):  
戴亚雨 DAI Ya-yu ◽  
高 林 GAO Lin ◽  
庞 泽 PANG Ze ◽  
李振杰 LI Zhen-jie ◽  
蔡明雷 CAI Ming-lei ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Applied Voltage ◽  
Dielectric Anisotropy

Broadband Reflection Gels Prepared from Microcapsules Containing Chiral Nematic Liquid Crystal with Negative Dielectric Anisotropy

2012 ◽  
Vol 27 (5) ◽  
pp. 583-589
Author(s):  
李克轩 LI Ke-xuan ◽  
王慧慧 WANG Hui-hui ◽  
张立培 ZHANG Li-pei ◽  
何万里 HE Wan-li ◽  
曹晖 CAO Hui ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Dielectric Anisotropy ◽  
Chiral Nematic
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