A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Combinations of liquid crystals and materials with unique features as well as properties at the nanoscale are reviewed. Particular attention is paid to recent developments, i.e., since 2007, in areas ranging from liquid crystal-nanoparticle dispersions to nanomaterials forming liquid crystalline phases after surface modification with mesogenic or promesogenic moieties. Experimental and synthetic approaches are summarized, design strategies compared, and potential as well as existing applications discussed. Finally, a critical outlook into the future of this fascinating field of liquid crystal research is provided.

Nanoparticles in liquid crystals and liquid crystalline nanoparticles.

In this review, we discuss new developments and recent trends in both amorphous and crystalline Al2O3 oxide nanofluids related to their phase dependent characteristics in detail. Nowadays, nanofluids have gained significant attention with the enhanced energy/heat efficiency, which is highly desirable to improve the performance of any energy based devices and technology. This review article systematically describes the various chemical synthesis routes followed by bottom-up approaches, surface morphologies, and detailed microstructure characteristics, and phase dependent thermal as well as optical properties for potential use of such materials in various applications.

Phase dependent thermal and spectroscopic responses of Al2O3 nanostructures with different morphogenesis.

Liquid crystal nanoscience, a field exploring the mutually beneficial combination of the unique properties of nanoscale materials and fluid, yet ordered liquid crystalline phases, is increasingly focusing on semiconductor quantum dots. In one major research thrust, the anisotropic properties of the liquid crystal host are sought to facilitate the assembly of quantum dots into arrays, in another, both size- and shape-dependent optical and electronic properties of quantum dots are used to manipulate optical, electro-optical and alignment properties of liquid crystalline materials. This feature article reviews recent accomplishments and new insights in this fascinating area of soft matter nanocomposites including work from our laboratory on a series of CdSe and CdTe quantum dots as additives in nematic liquid crystal hosts.

Quantum dots as liquid crystal dopants

Hysteresis-Free Blue Phase Liquid-Crystal-Stabilized by ZnS Nanoparticles

We present the results based on electro-optical properties of zinc oxide nanoparticles (ZnO-NPs) doped ferroelectric liquid crystal (FLC). It is observed that ZnO-NPs-FLC system has low operating voltage and improved optical contrast. The lowering in operating voltage and improvement in optical contrast has been attributed to larger dipole moment of ZnO-NPs that enhances the anchoring of FLC molecules around ZnO-NPs. The effect of ZnO-NPs on the material parameters of FLC has also been observed. These studies will certainly provide a tool to understand the interaction of ZnO-NPs with FLC molecules that can be utilized to fabricate low threshold electro-optic devices.

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Low power operation of ferroelectric liquid crystal system dispersed with zinc oxide nanoparticles

We present the characterisation and dielectric relaxation spectroscopy of a ferroelectric liquid crystal (FLC), namely KCFLC 7S. It was observed that the studied FLC material possesses the tendency of homeotropic alignment on glass substrates coated with indium tin oxide. A low frequency dielectric mode, along with the Goldstone mode, was observed in the SmC* phase of the FLC material. The low frequency mode became more dominant on doping gold nanoparticles into the FLC material. The occurrence of the low frequency mode was attributed to the ionisation–recombination-assisted diffusion of slow ions present in the FLC material. The behaviour of the relaxation frequency of the low frequency mode with applied dc bias and temperature was also demonstrated.

Low frequency dielectric relaxations of gold nanoparticles/ferroelectric liquid crystal composites

We observed that the doping of alumina nanoparticles (AL-NPs) has suppressed the undesired ionic effect in ferroelectric liquid crystals (FLCs). The pure and AL-NPs doped FLC cells were analysed by means of dielectric spectroscopy and electrical resistivity/conductivity measurements. Dielectric loss spectra confirmed the disappearance of the low-frequency relaxation peak, which appears due to the presence of ionic impurities in the FLC materials. The reduction of ionic effects has been attributed to the strong adsorption of ionic impurities on the surface of AL-NPs. The adsorption capability of AL-NPs has been studied with both the size and their concentration in FLC material. This study would be helpful to minimize the undesired ionic effects of LC-based display devices.

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Alumina nanoparticles find an application to reduce the ionic effects of ferroelectric liquid crystal

A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

/pdf/self-assembled-monolayer-based-liquid-crystal-biosensor-for-3w5caxcg1u.pdf

Tilak Joshi

Papers

Low power operation of ferroelectric liquid crystal system dispersed with zinc oxide nanoparticles

Low frequency dielectric relaxations of gold nanoparticles/ferroelectric liquid crystal composites

Alumina nanoparticles find an application to reduce the ionic effects of ferroelectric liquid crystal

Self assembled monolayer based liquid crystal biosensor for free cholesterol detection

Tuning the photoluminescence of ferroelectric liquid crystal by controlling the size of dopant ZnO quantum dots