Influence of Electric and Magnetic Fields on the Microwave Dielectric Constant of a Liquid Crystal with a Positive Dielectric Anisotropy

1965 ◽  
Vol 42 (2) ◽  
pp. 738-742 ◽  
Author(s):  
E. F. Carr
Keyword(s):  
Dielectric Constant ◽  
Liquid Crystal ◽  
Magnetic Fields ◽  
Dielectric Anisotropy ◽  
Microwave Dielectric ◽  
Electric And Magnetic Fields

scholarly journals Electric and Magnetic Field Effects in p-Methoxy Benzylidene p′-n-Butylaniline

1976 ◽  
Vol 31 (3-4) ◽  
pp. 283-287 ◽  
Author(s):  
N. V. S. Rao ◽  
P. R. Kishore ◽  
T. F. S. Raj ◽  
M. N. Avadhanlu ◽  
C. R. K. Murty
Keyword(s):  
Magnetic Field ◽  
Dielectric Constant ◽  
Liquid Crystal ◽  
Magnetic Fields ◽  
Nematic Liquid Crystal ◽  
Nematic Phase ◽  
Relative Effectiveness ◽  
Magnetic Field Effects ◽  
Electric And Magnetic Fields ◽  
Electric And Magnetic Field

Molecular alignment in the nematic phase of p-methoxy benzylidene p′-n-butylaniline (MBBA) in the presence of electric and magnetic fields is investigated. The relative effectiveness of electric and magentic fields on the nematic liquid crystal MBBA is discussed. In the dielectric regime it is found that the threshold fields for chevron formation are considerably different from the threshold fields for inducing changes in the dielectric constant.

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 Sensitivity of 6CHBT Liquid Crystal Doped with Ferroelectric or Magnetic Particles to Electric and Magnetic Fields

2014 ◽  
Vol 126 (1) ◽  
pp. 260-261 ◽  
Author(s):  
J. Majorošová ◽  
N. Tomašovičová ◽  
M. Timko ◽  
M. Koneracká ◽  
I.P. Studenyak ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Electric And Magnetic Fields

A study of the microwave dielectric permittivity of liquid crystals in electric and magnetic fields

1998 ◽  
Vol 43 (1) ◽  
pp. 105-109 ◽  
Author(s):  
B. A. Belyaev ◽  
N. A. Drokin ◽  
V. F. Shabanov ◽  
V. N. Shepov
Keyword(s):  
Liquid Crystals ◽  
Dielectric Permittivity ◽  
Magnetic Fields ◽  
Microwave Dielectric ◽  
Electric And Magnetic Fields

Layered anisotropic liquids: deformation of structures in electric and magnetic fields

2017 ◽  
Vol 12 (2) ◽  
pp. 214-218
Author(s):  
N.G. Migranov ◽  
D.V. Kondratyev
Keyword(s):  
Free Energy ◽  
Liquid Crystal ◽  
Magnetic Fields ◽  
Continuum Model ◽  
Polar Angle ◽  
Unit Vector ◽  
Ferroelectric Liquid Crystal ◽  
Anisotropic Layer ◽  
Electric And Magnetic Fields

On the basis of the analysis of the free energy of a viscoelastic anisotropic layer liquid, a chiral ferroelectric liquid crystal C^∗ , located in a thin cell in a ”bookshelf“ geometry the possibility of the smectic layers periodic distortions in the external magnetic H and electric E fields applied perpendicularly and along the plates, respectively, are investigated. The polar angle θ formed by the unit vector n and the normal a to the smectic planes is fixed, and the appearing Helfrich–Yuro distortions u of the smectic layers are assumed to be small in the proposed continuum model of the liquid ferroelectrics.

Measurement of elastic constants of nematic liquid crystals with use of hybrid in-plane-switched cell

2012 ◽  
Vol 20 (3) ◽  
Author(s):  
E. Nowinowski-Kruszelnicki ◽  
J. Kędzierski ◽  
Z. Raszewski ◽  
L. Jaroszewicz ◽  
M. Kojdecki ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Magnetic Fields ◽  
Electric Field ◽  
Elastic Constants ◽  
Nematic Liquid Crystals ◽  
Experimental Tests ◽  
New Method ◽  
Dielectric Anisotropy ◽  
Main Concept

AbstractA new method for quick and pretty accurate measurements of splay, twist and bend elastic constants of nematic liquid crystals is experimentally verified. The main concept relies on exploiting only the electric field and determining magnitudes of nematic elastic constants from threshold fields for Freedericksz transitions in only one hybrid in-plane-switched cell. In such cell the deformations of an investigated liquid crystal are controlled by three separated pairs of electrodes confining measurement domains. In two of them inter-digital electrodes are mounted on one cell cover. Splay, twist and bend elastic constants can be measured by a proper choice of electrodes’ configuration together with orienting cover coatings (without applying magnetic fields). In this paper, we describe layout of our cells and results of experimental tests by using different liquid crystals: 5CB and 6CHBT (with positive dielectric anisotropy), Demus’ esters (with negative dielectric anisotropy) and new liquid crystals mixtures produced in our university.

Phase Transitions in Liquid Crystal Doped with Magnetic Particles of Different Shapes in Combined Electric and Magnetic Fields

2014 ◽  
Vol 35 (11) ◽  
pp. 2044-2053 ◽  
Author(s):  
Natália Tomašovičová ◽  
Milan Timko ◽  
Vlasta Závišová ◽  
Anežka Hashim ◽  
Jan Jadzyn ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Liquid Crystal ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Electric And Magnetic Fields ◽  
Different Shapes

scholarly journals Fréederisksz Transitions in 6CB Based Ferronematics—Effect of Magnetic Nanoparticles Size and Concentration

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3096
Author(s):  
Katarína Zakutanská ◽  
Danil Petrov ◽  
Peter Kopčanský ◽  
Dorota Węgłowska ◽  
Natália Tomašovičová
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Magnetic Fields ◽  
Volume Concentration ◽  
Magnetization Vector ◽  
Oxide Nanoparticles ◽  
Capacitance Measurements ◽  
Electric And Magnetic Fields

In this paper, results acquired from capacitance measurements performed on composites based on nematic liquid crystal 4-cyano-40-hexylbiphenyl (6CB) and spherical iron oxide nanoparticles of various sizes are presented. Electric and magnetic Fréedericksz transitions, as well as structural transitions in combined electric and magnetic fields, were investigated. The obtained results showed the lowering of the threshold magnetic field with an increase in the volume concentration of nanoparticles. Estimations based on results obtained from measurements suggest soft anchoring between liquid crystal director and nanoparticles magnetization vector.

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