Liquid Crystals in Curved Confined Geometries: Microfluidics Bring New Capabilities for Photonic Applications and Beyond

Abstract

The quest for interesting properties and phenomena in liquid crystals toward their employment in nondisplay application is an intense and vibrant endeavor. Remarkable progress has recently been achieved with regard to liquid crystals in curved confined geometries, typically represented as enclosed spherical geometries and cylindrical geometries with an infinitely extended axial-symmetrical space. Liquid-crystal emulsion droplets and fibers are intriguing examples from these fields and have attracted considerable attention. It is especially noteworthy that the rapid development of microfluidics brings about new capabilities to generate complex soft microstructures composed of both thermotropic and lyotropic liquid crystals. This review attempts to outline the recent developments related to the liquid crystals in curved confined geometries by focusing on microfluidics-mediated approaches. We highlight a wealth of novel photonic applications and beyond and also offer perspectives on the challenges, opportunities, and new directions for future development in this emerging research area.

Applications of Microfluidics in Liquid Crystal-Based Biosensors

“…Additionally, the channel wall surface should be treated to be effectively wetted by the continuous phase to ensure the stable formation of LC droplets [88]. Moreover, by manipulation of the fluids within the microchannels and the design of microfluidic structures, some interesting and complex structures of LC droplets can be fabricated [89][90][91][92][93][94]. For example, by controlling the viscosity and flow rate of the poly (vinyl alcohol) (PVA) continuous phase inside a co-flow geometry, Takanaka and coworkers prepared a necklace-like structure, in which PVA-stabilized LC droplets connected by thin tethers made up of PVA and LC in one step (Figure 5a) [93].…”

Advances in the Supramolecular Chemistry of Tetracoordinate Boron-Containing Organic Molecules into Organogels and Mesogens

“…While LCs are immensely popular for their application in flat panel displays, their special properties have been used in a number of other applications as well such as organic electronics, nanoparticle organization, LC colloids, LC elastomer actuators, and chemical and biological sensors. Apart from these, liquid crystals have also found utility in thin-film thermometers and switchable display windows ( Lagerwall and Scalia, 2012 ; Iino et al, 2015 ; Urbanski et al, 2017 ; Chen et al, 2021 ).…”

A Mobile and Self‐Powered Micro‐Flow Pump Based on Triboelectricity Driven Electroosmosis

“…The microfluidic system is an experimental platform that integrates the processes of biological/chemical/medical/ environmental reactions, separation, and detection into a small chip with designed microchannels, called "lab on a chip", which has been extensively investigated and developed in many research fields. [1][2][3][4][5][6][7][8][9][10][11] In microfluidic systems, a micro-flow pump that drives the controllable micro-flow is the core component and shows the greatest significance. [12][13][14] Among various driving mechanisms, electroosmotic pumps (EOP) are widely employed in microfluidic systems due to their advantages of easy fabrication, constant fluid velocity and high integratability compared with mechanical-pressure and thermal-gradient driven approaches.…”