Field-controlled dynamics of skyrmions and monopoles
Tai, Jung-Shen B., Andrew J. Hess, Jin-Sheng Wu, and Ivan I. Smalyukh. Field-controlled dynamics of skyrmions and monopoles. Science Advances 10, no. 4 (2024): eadj9373.
The search for magnetic monopoles as elementary particles is at the heart of much of the ongoing experimental research. In condensed matter systems, it has inspired the discovery of analogous excitations as well. For example, in chiral systems, emerging monopoles can be credited for the transitions happening between topologically distinct states, for example, a transition to A-phase comprising periodic arrays of skyrmions, from helical and conical phase. With the help of optical characterisation and numerical modelling, the authors demonstrate that the realisation of different geometrical configurations of skyrmions that terminate at monopoles can be realised in liquid crystals and liquid crystal ferromagnets. The manipulation of these structures via magnetic and electric fields is also demonstrated.
Modeling the light-powered self-rotation of a liquid crystal elastomer fiber-based engine
Yu, Yong, Haoyu Hu, Yuntong Dai, and Kai Li. Modeling the light-powered self-rotation of a liquid crystal elastomer fibre-based engine. Physical Review E 109, no. 3 (2024): 034701.
Because of the self-oscillating systems’ ability to convert ambient energy directly to mechanical energy, it is imperative to design new types of self-oscillating systems for practical applications in energy harvesters, engines and actuators. Building on the concept of a four-stroke engine, the authors in this paper present a self-rotating engine concept based on photothermally responsive materials, consisting of liquid crystal elastomer (LCE) fibre, which, under steady illumination, can self-rotate. This nonlinear theoretical model of the LCE-based engine is based on the photo-thermal-mechanical model. According to numerical calculations, a supercritical Hopf bifurcation is experienced between the static and self-rotation regime. The continuity of the periodic motion is sustained by the correlation between damping dissipation and photothermal energy. The advantage of this engine over the plethora of other self-oscillating systems lies in its simple, lightweight structure, customisable dimensions, high spend and a broader range of design concepts.
Moire effect enables versatile design of topological defects in nematic liquid crystals
Wang, Xinyu, Jinghua Jiang, Juan Chen, Zhawure Asilehan, Wentao Tang, Chenhui Peng, and Rui Zhang. Moiré effect enables versatile design of topological defects in nematic liquid crystals. Nature Communications 15, no. 1 (2024): 1655.
Liquid crystal surface-patterning techniques have given rise to the creation of precise topological defects with many emergent applications. However, what still needs much attention is the manipulation and application of these defects. The authors in this paper utilise the Moire effect in patterned nematic liquid crystal cells to create topological defects. With the use of experiment and simulation, nematic cells consisting of substrates patterned by periodic surface anchoring – achieved by rotating one surface against the other – are observed to show a diversity of highly tunable, novel topological defects. 3D self-assembly of colloids is guided by these defects which, in turn, prevents the self-annihilation of loop defects by jamming. It is further demonstrated that certain cells moire cells can give rise to arbitrary shapes that are represented by defect regions.
A blue phase liquid crystal film based on an interpenetrating network and its sensitive humidity response performance
Hu, Wentuo, Wanli He, Kainan Wang, Changli Zhang, Zhou Yang, Yuzhan Li, Hui Cao, and Dong Wang. A blue phase liquid crystal film based on an interpenetrating network and its sensitive humidity response performance. Materials Advances (2024).
A blue phase liquid crystal polymer film is fabricated which is based on an interpenetrating polymer system and showcases sensitivity to humidity. To manipulate the nanostructure of the blue phase polymer, the authors use interpenetrating networks (IPNs) by sequentially synthesising it into a humidity sensitive acrylic acid, which shows sensitivity to humidity changes. Investigation of the moisture response ability of the film is carried out by examining different influencing factors as well as looking into the colour and shape changes that the humidity induces. The authors compare the micromorphology and humidity affected reflectance changes of the blue phases to the cholesteric phase samples. Overall, the film’s potential for advanced applications like sensors and displays is demonstrated by the fact that it not only exhibits humidity-induced colour changes but also has an excellent deformation response time.
A fully self-powered ocean wave observation system empowered by natural light modulated by a friction-driven polymer network liquid crystal
Chen, Xingwen, Jiaqi Wang, Cuiling Meng, Pengcheng Liu, Yifan Sun, Xinghui Qin, and Shixing Xie. A Fully Self-Powered Ocean Wave Observation System Empowered by Natural Light Modulated by a Friction-Driven Polymer Network Liquid Crystal. ACS Applied Materials & Interfaces (2024).
Typical ocean wave observation instruments currently have certain energetic and environmental costs that warrant the need for a change in the system. For instance, the batteries used in such instruments limit continuous observation times on top of being an environmental contaminant. Triboelectric nanogenerators (TENGs) work is by utilising triboelectric charge as the information carrier. However, the drawback to that is the need for amplification, which in turn consumes more energy. The authors in this paper, overcome the problem by choosing photons as the energy carrier rather than electrons to develop a fully self-powered natural light-enabled sensing system for ocean wave monitoring. This is achieved by coupling a polymer network liquid crystal (PNLC)-triggered optical system to two rotatory-freestanding sliding TENGs (RFS-TENGs).