Design and applications of light responsive liquid crystal polymer thin films

Abstract

Responding to external stimuli is a trait observed in all living organisms. Modern artificial materials have adopted this profound characteristic, thereby commencing the field of stimuli-responsive systems. Liquid crystal polymers are attractive members of this family of systems owing to the available control on their anisotropic properties capable of generating complex morphologies under external stimuli. Liquid crystal polymer systems have been designed to respond to various stimuli such as heat, light, pH, humidity, and electric and magnetic fields. The attainable shapes and topographies open exciting possibilities for novel applications in a wide range of different fields such as microfluidics, artificial muscles, haptics, and optical functions. The microstructural design of liquid crystal polymers leading to diverse applications is the focus of this review. We conclude by presenting the future prospects and developments in these promising material systems.

Microfluidic Applications of Artificial Cilia: Recent Progress, Demonstration, and Future Perspectives

“…Even though the in-depth information and uses of artificial cilia in transportation, moving, and sensing will be seen in the upcoming chapters, the insights into the evolvement of artificial cilia from natural cilia are explained here by detailing their participation with examples of each significant application. Wang et al [ 15 ] fabricated magnetically actuated cilia using Polydimethylsiloxane (PDMS) and cobalt powder by biomimicking cactus spines and trachea cilia in favor of transportation. The artificial cilia were capable of transporting hydrogel slices directionally using their anisotropic surface and asymmetric motion.…”

“…The existing reviews on microfluidic based devices focused on any specific topics. For instance, the studies were focused on particular actuation techniques like magnetics [ 10 , 11 , 12 , 13 , 14 ] and light [ 15 ], specific applications like mixing [ 12 ], robotics [ 16 ] and particle manipulation [ 11 , 17 , 18 ], or fabrication techniques like 3D printing [ 19 ]. Few excellent reviews are presented in the field of artificial cilia-based microfluidic devices [ 20 , 21 ].…”

Regulating Surface Topography of Liquid‐Crystalline Polymers by External Stimuli

“…In terms of Young's modulus of LCP in one well‐oriented state, the highest is along the director, while the lowest is perpendicular to the director, exhibiting anisotropic behaviors. [ 35 ] LCP in the randomly aligned state has a modulus between the two above‐mentioned situations. The difference in elastic modulus can lead to an anisotropic deformation when subjected to external forces.…”

“…Possible ways can be the anisotropy of LC director, the concentration gradient of materials in film, or the difference of light illumination. [ 35 ] As shown in Figure a, by introducing vertical molecular orientation into the cholesteric LC film in a periodic way, the SRG was enhanced. [ 59 ] In the chiral nematic area, molecules were in‐plane oriented.…”

An ultrahigh fatigue resistant liquid crystal elastomer-based material enabled by liquid metal

“…Liquid crystal elastomer (LCE) [1][2][3][4][5][6][7][8][9][10][11][12][13][14], as an extraordinary type of polymeric material combining the anisotropic order of mesogen and the entropy elasticity of elastomer, can exhibit large and reversible shape morphing in response to external stimuli such as heat, light, humidity, electricity, and magnetic field. This remarkable two-way shape memory function endows LCE materials with potential applications in actuators, sensors, micromechanical systems, soft robotic technology, etc.…”