Laser-directed hierarchical assembly of liquid crystal defects and control of optical phase singularities

Topological defect lines are ubiquitous and important in a wide variety of fascinating phenomena and theories in many fields ranging from materials science to early-universe cosmology, and to engineering of laser beams. However, they are typically hard to control in a reliable manner. Here we describe facile erasable “optical drawing” of self-assembled defect clusters in liquid crystals. These quadrupolar defect clusters, stabilized by the medium's chirality and the tendency to form twisted configurations, are shaped into arbitrary two-dimensional patterns, including reconfigurable phase gratings capable of generating and controlling optical phase singularities in laser beams. Our findings bridge the studies of defects in condensed matter physics and optics and may enable applications in data storage, singular optics, displays, electro-optic devices, diffraction gratings, as well as in both optically- and electrically-addressed pixel-free spatial light modulators

Morphing in nature and beyond: a review of natural and synthetic shape-changing materials and mechanisms

Shape-changing materials open an entirely new solution space for a wide range of disciplines: from architecture that responds to the environment and medical devices that unpack inside the body, to passive sensors and novel robotic actuators. While synthetic shape-changing materials are still in their infancy, studies of biological morphing materials have revealed key paradigms and features which underlie efficient natural shape-change. Here, we review some of these insights and how they have been, or may be, translated to artificial solutions. We focus on soft matter due to its prevalence in nature, compatibility with users and potential for novel design. Initially, we review examples of natural shape-changing materials—skeletal muscle, tendons and plant tissues—and compare with synthetic examples with similar methods of operation. Stimuli to motion are outlined in general principle, with examples of their use and potential in manufactured systems. Anisotropy is identified as a crucial element in directing shape-change to fulfil designed tasks, and some manufacturing routes to its achievement are highlighted. We conclude with potential directions for future work, including the simultaneous development of materials and manufacturing techniques and the hierarchical combination of effects at multiple length scales.</p

Liquid crystal dye mixture

A guest-host liquid crystal dye mixture comprising a calamatic, thermotropic liquid crystal as host and a dichroic fluorescent dye as guest, characterized in that the dichroic fluorescent dye is a multichromophoric dye containing at least a group with the general formula Ry - X1 - C1, wherein Ry is a chromophore from the rylene family, C1 is a second chromophore and X1 is a spacer that interrupts the conjugation between Ry and C1, the spacer X1 is selected such that it introduces rigidity against bending or folding over an axis perpendicular to the length of the molecule

Optical device with anisotropic luminescent material

An optical device (1) is provided. The optical device comprising a switchable layer (2) at least one alignment layer (6) a light guiding system (5), whereas the switchable layer (2) comprises a luminescent material (3) for absorbing and emitting light, whereby the alignment of the luminescent material (3) is changeable and the light guiding system (5) guides the emitted light, whereby the switchable layer (2) is in contact with the at least one alignment layer (6) and the luminescent material (3) exhibits anisotropic properties, whereby the optical device (1) comprises a light energy-converting means (7), wherein the light guiding system (5) is in physical contact with the energy converting means (7)

Multifunctional optical sensor

The invention relates to a multifunctional optical sensor, having at least 2 areas which independently react to different input parameters, the sensor comprising a substrate and a polymeric layer comprising polymerized liquid crystal monomers having an ordered morphology, wherein the color, the reflectivity or the birefringence of the sensor changes due to a change of the morphology, wherein said change of the morphology is caused by physical contact with a chemical agent such as a gas or liquid a change of temperature, or passage of time. The invention also relates to a process for the preparation of the sensor and for the use of a film comprising a single substrate, a layer having a cholesteric liquid crystalline structure for application in labels for packaging of perishable goods, food, fine chemicals, bio-medical materials

Conversion of light into macroscopic helical motion.

A key goal of nanotechnology is the development of artificial machines capable of converting molecular movement into macroscopic work. Although conversion of light into shape changes has been reported and compared to artificial muscles, real applications require work against an external load. Here, we describe the design, synthesis and operation of spring-like materials capable of converting light energy into mechanical work at the macroscopic scale. These versatile materials consist of molecular switches embedded in liquid-crystalline polymer springs. In these springs, molecular movement is converted and amplified into controlled and reversible twisting motions. The springs display complex motion, which includes winding, unwinding and helix inversion, as dictated by their initial shape. Importantly, they can produce work by moving a macroscopic object and mimicking mechanical movements, such as those used by plant tendrils to help the plant access sunlight. These functional materials have potential applications in micromechanical systems, soft robotics and artificial muscles