P‐12.16: New Liquid Crystal Materials with Large Values of Dielectric Anisotropy in the Gigahertz Range for High‐frequency Devices

The operation of the radar technology is based on the mechanical movement of the antenna. To overcome the flaw of the mechanical movement an electronically tunable reflectarray antenna based on non-linear properties of Liquid Crystal materials has been introduced. This paper presents a detailed analysis of the tunability performance of different X-band reflectarray resonant elements printed on 1 mm thick grounded Liquid Crystal materials. Dynamic phase range and frequency tunabilty of rectangular, dipole and ring elements have been investigated by using CST computer model. Non-linear material properties have been used to develop an algorithm based on Method of Moment, for dynamic phase distribution of three resonant elements. It has been shown that the ring element offers a maximum dynamic phase range of 248° as compared to dipole and rectangular elements which offer 238° and 160° respectively. Moreover a maximum frequency tunabilty of 796 MHz, 784 MHz and 716 MHz can be achieved for rectangular, dipole and ring elements respectively with a dielectric anisotropy of 0.45. Waveguide simulator measurements of passive reflectarray unit cells demonstrate that rectangular element is observed to offer a minimum reflection loss of 1.6 dB as compared to dipole and ring elements which offer 3.3 dB and 3.6 dB respectively.

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Influence of Stabilizing Magnetic Field on the Domain Formation in Nematic Liquid Crystal Materials with Positive Dielectric Anisotropy

Molecular Crystals and Liquid Crystals Science and Technology Section A Molecular Crystals and Liquid Crystals ◽

10.1080/10587250108028628 ◽

2001 ◽

Vol 367 (1) ◽

pp. 101-112

Author(s):

P. R. Kishore

Keyword(s):

Magnetic Field ◽

Liquid Crystal ◽

Nematic Liquid Crystal ◽

Dielectric Anisotropy ◽

Domain Formation ◽

Liquid Crystal Materials

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Novel liquid-crystal materials with negative dielectric anisotropy for TV application

Journal of the Society for Information Display ◽

10.1889/1.2210801 ◽

2006 ◽

Vol 14 (6) ◽

pp. 517 ◽

Cited By ~ 11

Author(s):

Matthias Bremer ◽

Melanie Klasen-Memmer ◽

Detlef Pauluth ◽

Kazuaki Tarumi

Keyword(s):

Liquid Crystal ◽

Dielectric Anisotropy ◽

Liquid Crystal Materials

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Linear Low Density Polyethylene-Thermotropic Liquid Crystal Composite Substrate for High-Frequency Devices: Dielectric Characterization

Journal of Electronic Materials ◽

10.1007/s11664-020-08626-5 ◽

2021 ◽

Author(s):

Pulin Dutta ◽

Bhaben Saikia ◽

Parameswara Rao Alapati ◽

Kunal Borah

Keyword(s):

Liquid Crystal ◽

High Frequency ◽

Low Density Polyethylene ◽

Low Density ◽

Linear Low Density Polyethylene ◽

Dielectric Characterization ◽

Thermotropic Liquid Crystal ◽

Composite Substrate ◽

High Frequency Devices ◽

Crystal Composite

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

Biosensors ◽

10.3390/bios11030081 ◽

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.

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