Voltage-Induced Vorticity and Optical Focusing in Liquid Crystals

Penz, P. Andrew

doi:10.1103/physrevlett.24.1405

Cited by 128 publications

(23 citation statements)

References 9 publications

(8 reference statements)

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“…1A(b)), indicating the formation of stationary EHC rolls, often referred to as Williams domains. [24][25][26][27] The EHC develops due to effects resulting from a positive conductivity anisotropy and a negative dielectric anisotropy. The micrograph of Fig.…”

Section: Microscope Characterizationmentioning

confidence: 99%

“…In order to gain insight into the precise position of the colloidal chain within the EHC rolls, we have studied cells with a larger thickness. Since the rotation of the EHC rolls slows down with increasing cell thickness, 26 the undulated structure of the chain can be studied in thicker cells in a quasi-static configuration, moving only with a minor velocity. Fig.…”

Section: Caterpillar Motion Of Colloidal Chainsmentioning

confidence: 99%

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Colloidal caterpillars for cargo transportation

et al. 2014

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Tunable transport of tiny objects in fluid systems is demanding in diverse fields of science such as drug delivery, active matter far from equilibrium, and lab-on-a-chip applications. Here, we report the directed motion of colloidal particles and self-assembled colloidal chains in a nematic liquid crystal matrix using electrohydrodynamic convection (EHC) rolls. The asymmetric distortion of the molecular orientation around the particles results -for single particles -in a hopping motion from one EHC roll to the next and -for colloidal chains -in a caterpillar-like motion in the direction perpendicular to the roll axes. We demonstrate the use of the colloidal chains as micro traction engines for the transport of various types of micro cargo.

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Section: Microscope Characterizationmentioning

confidence: 99%

Section: Caterpillar Motion Of Colloidal Chainsmentioning

confidence: 99%

Colloidal caterpillars for cargo transportation

et al. 2014

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“…[41][42][43] It is difficult to pin point the very first work that studied nematic LCs as gratings since several of them did not focus on the diffractive characteristics. For this reason, many of the development made in the LC field involves nematic LCs first.…”

Section: Surface Template and Electric Field-driven Gratingsmentioning

confidence: 99%

“…One of the first evidences that LCs could be used as gratings arose when it was discovered that a lowfrequency electric field applied to some nematic LCs (with the correct dielectric and conductivity anisotropies) could present distinct hydrodynamic instabilities in which the material organizes itself as a periodic lattice of domains (or stripes). [41][42][43] It is difficult to pin point the very first work that studied nematic LCs as gratings since several of them did not focus on the diffractive characteristics. Nevertheless, researchers started paying attention to it by the end of the 1960s.…”

Section: Surface Template and Electric Field-driven Gratingsmentioning

confidence: 99%

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

et al. 2018

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the duality consolidation, the idea of controlling light and how it interacts with matter has always been an exciting topic. Visible light, as we perceive it, is a small portion of the electromagnetic spectrum composed of mutually perpendicular oscillating electric and magnetic fields that propagate through space and presents wave-like and particle-like behavior. Since the elements comprising matter possess dynamic electron clouds, the electromagnetic nature of light prompts different responses when it interacts with different materials, depending on its intensity, frequency, the arrangement of molecules, and so on. Whenever light interacts with matter, it might be absorbed, re-emitted, scattered, or transmitted. Although these effects are well known, the combination of them with new, innovative materials pushes optics forward. In fact, advances in optics have often occurred through the development of materials with improved optical properties, thus creating remarkable applications that tremendously influence our daily lives. These exciting applications include image processing and recording, lasing, data storage, display devices, detector systems, propulsion systems, and optical tweezers, which have enabled remote micromanipulation of colloidal particles and promising applications in various biomedical and biological applications. [1][2][3] There is, however, one component that stands out: the diffraction grating. It is generally regarded as one of the most important devices in the development of several fields of science. [4] Such importance comes from the fact that a diffraction grating is a device with a periodic structure capable of changing the propagation and splitting the spectrum The ability to control light direction with tailored precision via facile means is long-desired in science and industry. With the advances in optics, a periodic structure called diffraction grating gains prominence and renders a more flexible control over light propagation when compared to prisms. Today, diffraction gratings are common components in wavelength division multiplexing devices, monochromators, lasers, spectrometers, media storage, beam steering, and many other applications. Next-generation optical devices, however, demand nonmechanical, full and remote control, besides generating higher than 1D diffraction patterns with as few optical elements as possible. Liquid crystals (LCs) are great candidates for light control since they can form various patterns under different stimuli, including periodic structures capable of behaving as diffraction gratings. The characteristics of such gratings depend on several physical properties of the LCs such as film thickness, periodicity, and molecular orientation, all resulting from the internal constraints of the sample, and all of these are easily controllable. In this review, the authors summarize the research and development on stimuli-controllable diffraction gratings and beam steering using LCs as the active optical materials. Dynamic gratings fabricated by applying external f...

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“…This phenomenon can produce regular domain patterns (6) which exhibit vortex motion (56) or may produce a state of random turbulence which is referred to as dynamic scattering (57). Since both processes involve physical motion of the liquid, either could lower CI by contributing to convective mass transport of the solute.…”

Section: Discuss10 Nmentioning

confidence: 99%

Chromatographic Behavior of a Cholesteryl Myristate Stationary Phase in an Electric Field

1975

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Changes in peak shape which accompany the imposition of an electric field were examined by moments analysis. Although peak maxima shifted signficantly, only slight changes were observed in the value of the peak mean. Column efficiencies calculated from the second central moment indicated that the field lowered the resistance to mass transfer, probably as a result of electric field-induced convection of the stationary phase.

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Voltage-Induced Vorticity and Optical Focusing in Liquid Crystals

Cited by 128 publications

References 9 publications

Colloidal caterpillars for cargo transportation

Colloidal caterpillars for cargo transportation

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

Chromatographic Behavior of a Cholesteryl Myristate Stationary Phase in an Electric Field

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