scholarly journals Topology control of human fibroblast cells monolayer by liquid crystal elastomer

2020 ◽  
Vol 6 (20) ◽  
pp. eaaz6485 ◽  
Author(s):  
Taras Turiv ◽  
Jess Krieger ◽  
Greta Babakhanova ◽  
Hao Yu ◽  
Sergij V. Shiyanovskii ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Orientational Order ◽  
Topological Defects ◽  
Density Fluctuations ◽  
Dermal Fibroblasts ◽  
Produce Cell ◽  
Surface Anchoring ◽  
Liquid Crystal Elastomer ◽  
Anisotropic Surface ◽  
Living Tissues

Eukaryotic cells in living tissues form dynamic patterns with spatially varying orientational order that affects important physiological processes such as apoptosis and cell migration. The challenge is how to impart a predesigned map of orientational order onto a growing tissue. Here, we demonstrate an approach to produce cell monolayers of human dermal fibroblasts with predesigned orientational patterns and topological defects using a photoaligned liquid crystal elastomer (LCE) that swells anisotropically in an aqueous medium. The patterns inscribed into the LCE are replicated by the tissue monolayer and cause a strong spatial variation of cells phenotype, their surface density, and number density fluctuations. Unbinding dynamics of defect pairs intrinsic to active matter is suppressed by anisotropic surface anchoring allowing the estimation of the elastic characteristics of the tissues. The demonstrated patterned LCE approach has potential to control the collective behavior of cells in living tissues, cell differentiation, and tissue morphogenesis.

Deuteron NMR investigation on orientational order parameter in polymer dispersed liquid crystal elastomers

2020 ◽  
Vol 22 (40) ◽  
pp. 23064-23072
Author(s):  
Andraž Rešetič ◽  
Jerneja Milavec ◽  
Valentina Domenici ◽  
Blaž Zupančič ◽  
Alexej Bubnov ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Orientational Order ◽  
Orientational Order Parameter ◽  
Liquid Crystal Elastomer ◽  
H Nmr ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Liquid Crystal Elastomers ◽  
Magnetically Aligned

Orientational order parameter of magnetically aligned liquid crystal elastomer particles suspended in a cured silicone matrix is assessed using 2H-NMR spectroscopy. Obtained results correspond well with the composite's thermomechanical response.

scholarly journals Prolate and oblate chiral liquid crystal spheroids

2020 ◽  
Vol 6 (28) ◽  
pp. eaba6728
Author(s):  
Monirosadat Sadati ◽  
Jose A. Martinez-Gonzalez ◽  
Ye Zhou ◽  
Nader Taheri Qazvini ◽  
Khia Kurtenbach ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Wearable Sensors ◽  
Mechanical Strain ◽  
Orientational Order ◽  
Topological Defects ◽  
Smart Fabrics ◽  
Chiral Liquid Crystal ◽  
Smart Coatings ◽  
Optical Appearance

Liquid crystals are known to exhibit intriguing textures and color patterns, with applications in display and optical technologies. This work focuses on chiral materials and examines the palette of morphologies that arises when microdroplets are deformed into nonspherical shapes in a controllable manner. Specifically, geometrical confinement and mechanical strain are used to manipulate orientational order, phase transitions, and topological defects that arise in chiral liquid crystal droplets. Inspired by processes encountered in nature, where insects and animals often rely on strain and temperature to alter the optical appearance of dispersed liquid crystalline elements, chiral droplets are dispersed in polymer films and deformation induced by uniaxial or biaxial stretching. Our measurements are interpreted by resorting to simulations of the corresponding systems, thereby providing an in-depth understanding of the morphologies that arise in these materials. The reported structures and assemblies offer potential for applications in smart coatings, smart fabrics, and wearable sensors.

scholarly journals Periodic assembly of nanoparticle arrays in disclinations of cholesteric liquid crystals

2017 ◽  
Vol 114 (9) ◽  
pp. 2137-2142 ◽  
Author(s):  
Yunfeng Li ◽  
Elisabeth Prince ◽  
Sangho Cho ◽  
Alinaghi Salari ◽  
Youssef Mosaddeghian Golestani ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Self Assembly ◽  
Soft Matter ◽  
Cholesteric Liquid Crystal ◽  
Topological Defects ◽  
Spatial Inhomogeneity ◽  
Cholesteric Phase ◽  
Anisotropic Surface ◽  
Linear Defects

An important goal of the modern soft matter science is to discover new self-assembly modalities to precisely control the placement of small particles in space. Spatial inhomogeneity of liquid crystals offers the capability to organize colloids in certain regions such as the cores of the topological defects. Here we report two self-assembly modes of nanoparticles in linear defects-disclinations in a lyotropic colloidal cholesteric liquid crystal: a continuous helicoidal thread and a periodic array of discrete beads. The beads form one-dimensional arrays with a periodicity that matches half a pitch of the cholesteric phase. The periodic assembly is governed by the anisotropic surface tension and elasticity at the interface of beads with the liquid crystal. This mode of self-assembly of nanoparticles in disclinations expands our ability to use topological defects in liquid crystals as templates for the organization of nanocolloids.

scholarly journals Surface anchoring controls orientation of a microswimmer in nematic liquid crystal

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Hai Chi ◽  
Mykhailo Potomkin ◽  
Lei Zhang ◽  
Leonid Berlyand ◽  
Igor S. Aranson
Keyword(s):  
Liquid Crystal ◽  
Critical Case ◽  
Topological Defects ◽  
Water Soluble ◽  
Critical Surface ◽  
Bacteria Transport ◽  
Surface Anchoring ◽  
Swimming Direction ◽  
Anchoring Strength ◽  
Surface Anchoring Strength

Abstract Microscopic swimmers, both living and synthetic, often dwell in anisotropic viscoelastic environments. The most representative realization of such an environment is water-soluble liquid crystals. Here, we study how the local orientation order of liquid crystal affects the motion of a prototypical elliptical microswimmer. In the framework of well-validated Beris-Edwards model, we show that the microswimmer’s shape and its surface anchoring strength affect the swimming direction and can lead to reorientation transition. Furthermore, there exists a critical surface anchoring strength for non-spherical bacteria-like microswimmers, such that swimming occurs perpendicular in a sub-critical case and parallel in super-critical case. Finally, we demonstrate that for large propulsion speeds active microswimmers generate topological defects in the bulk of the liquid crystal. We show that the location of these defects elucidates how a microswimmer chooses its swimming direction. Our results can guide experimental works on control of bacteria transport in complex anisotropic environments.

scholarly journals The rise of Newtonian drops in a nematic liquid crystal

2007 ◽  
Vol 593 ◽  
pp. 385-404 ◽  
Author(s):  
CHUNFENG ZHOU ◽  
PENGTAO YUE ◽  
JAMES J. FENG
Keyword(s):  
Liquid Crystal ◽  
Flow Field ◽  
Point Defect ◽  
Nematic Liquid Crystal ◽  
Topological Defects ◽  
Diffuse Interface ◽  
Initial Surface ◽  
Surface Anchoring ◽  
Moving Interface ◽  
The Stability

We simulate the rise of Newtonian drops in a nematic liquid crystal parallel to the far-field molecular orientation. The moving interface is computed in a diffuse-interface framework, and the anisotropic rheology of the liquid crystal is represented by the Leslie–Ericksen theory, regularized to permit topological defects. Results reveal interesting coupling between the flow field and the orientational field surrounding the drop, especially the defect configuration. The flow generally sweeps the point and ring defects downstream, and may transform a ring defect into a point defect. The stability of these defects and their transformation are depicted in a phase diagram in terms of the Ericksen number and the ratio between surface anchoring and bulk elastic energies. The nematic orientation affects the flow field in return. Drops with planar anchoring on the surface rise faster than those with homeotropic anchoring, and the former features a vortex ring in the wake. These are attributed to the viscous anisotropy of the nematic. With homeotropic anchoring, the drop rising velocity experiences an overshoot, owing to the transformation of the initial surface ring defect to a satellite point defect. With both types of anchoring, the drag coefficient of the drop decreases with increasing Ericksen number as the flow-alignment of the nematic orientation reduces the effective viscosity of the liquid crystal.

Anisotropic Surface Anchoring Conditions for Gray-Scale Capability in High-Tilt-Angle Ferroelectric Liquid Crystal

1995 ◽  
Vol 34 (Part 1, No. 7A) ◽  
pp. 3602-3606 ◽  
Author(s):  
Haridas E. P. ◽  
Sukhwant Singh Bawa ◽  
Ashok Manikrao Biradar ◽  
Subhas Chandra
Keyword(s):  
Liquid Crystal ◽  
Tilt Angle ◽  
Ferroelectric Liquid Crystal ◽  
Gray Scale ◽  
Surface Anchoring ◽  
Anisotropic Surface

scholarly journals Mosaics of topological defects in micropatterned liquid crystal textures

2018 ◽  
Vol 4 (11) ◽  
pp. eaau8064 ◽  
Author(s):  
Dae Seok Kim ◽  
Simon Čopar ◽  
Uroš Tkalec ◽  
Dong Ki Yoon
Keyword(s):  
Liquid Crystal ◽  
Orientational Order ◽  
Topological Defects ◽  
Smectic Phase ◽  
Dimensional System ◽  
Two Dimensional ◽  
Layer Spacing ◽  
Smectic A ◽  
Lattice Symmetry ◽  
Two Dimensional System

Topological defects in the orientational order that appear in thin slabs of a nematic liquid crystal, as seen in the standard schlieren texture, behave as a random quasi–two-dimensional system with strong optical birefringence. We present an approach to creating and controlling the defects using air pillars, trapped by micropatterned holes in the silicon substrate. The defects are stabilized and positioned by the arrayed air pillars into regular two-dimensional lattices. We explore the effects of hole shape, lattice symmetry, and surface treatment on the resulting lattices of defects and explain their arrangements by application of topological rules. Last, we show the formation of detailed kaleidoscopic textures after the system is cooled down across the nematic–smectic A phase transition, frustrating the defects and surrounding structures with the equal-layer spacing condition of the smectic phase.

scholarly journals Light-Actuated Liquid Crystal Elastomer Prepared by Projection Display

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7245
Author(s):  
Juan Chen ◽  
Oluwafemi Isaac Akomolafe ◽  
Jinghua Jiang ◽  
Chenhui Peng
Keyword(s):  
Liquid Crystal ◽  
Three Dimensional ◽  
Topological Defects ◽  
Soft Materials ◽  
Liquid Crystal Elastomer ◽  
Projection Display ◽  
Liquid Crystal Elastomers ◽  
Spatially Varying ◽  
External Stimuli ◽  
3D Shapes

Soft materials with programmability have been widely used in drug delivery, tissue engineering, artificial muscles, biosensors, and related biomedical engineering applications. Liquid crystal elastomers (LCEs) can easily morph into three-dimensional (3D) shapes by external stimuli such as light, heat, and humidity. In order to program two-dimensional (2D) LCE sheets into desired 3D morphologies, it is critical to precisely control the molecular orientations in LCE. In this work, we propose a simple photopatterning method based on a maskless projection display system to create spatially varying molecular orientations in LCE films. By designing different synchronized rotations of the polarizer and projected images, diverse configurations ranging from individual to 2D lattice of topological defects are fabricated. The proposed technique significantly simplified the photopatterning procedure without using fabricated masks or waveplates. Shape transformations such as a cone and a truncated square pyramid, and functionality mimicking the responsive Mimosa Pudica are demonstrated in the fabricated LCE films. The programmable LCE morphing behaviors demonstrated in this work will open opportunities in soft robotics and smart functional devices.

Temperature influence on homogeneous instabilities in stationary shear flow of nematic liquid crystal with weak surface anchoring

2010 ◽  
Vol 7 ◽  
pp. 191-201
Author(s):  
I.Sh. Nasibullayev ◽  
O.V. Urina
Keyword(s):  
Liquid Crystal ◽  
Shear Flow ◽  
Nematic Liquid Crystal ◽  
Effect Of Temperature ◽  
External Fields ◽  
Temperature Influence ◽  
Surface Anchoring ◽  
Weak Surface ◽  
Surface Coupling

Plane stationary shear flow of the nematic liquid crystal with weak surface anchoring is investigated. The effect of temperature, external fields, and the nature of the surface coupling on the formation of orientation instabilities is investigated.

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