Liquid crystal elastomers (LCEs) are of considerable interest for their potential as actuators, due to the ability of aligned monodomain LCEs to reversibly change their bulk dimensions in response to a phase change. Many LCEs reported in the literature will contract in one dimension in response to a temperature change or irradiation with ultraviolet light. For practical applications, photo-actuation is a more useful technology than thermal actuation due to the achievable speed and localization of the response. The use of UV light sources to ‘switch’ the materials is impractical, however, due to considerations of both safety and cost. Sensitization of LCEs to light of higher wavelengths may be achieved by mixing a small concentration of carbon nanotubes (CNTs) into the polymer matrix; CNTs will absorb light over a large range of wavelengths, and convert it into local heat, thus triggering the required phase changes in the LCE. In this article we demonstrate that a low concentration of multi-walled CNTs does not affect the thermal response of the polymers but does significantly enhance their response to infra-red (IR) and visible light.

Advances in nanoscale magnetism increasingly require characterization tools providing detailed descriptions of magnetic configurations. Magnetic transmission X-ray microscopy produces element specific magnetic domain images with nanometric lateral resolution in films up to ∼100 nm thick. Here we present an imaging method using the angular dependence of magnetic contrast in a series of high resolution transmission X-ray microscopy images to obtain quantitative descriptions of the magnetization (canting angles relative to surface normal and sense). This method is applied to 55–120 nm thick ferromagnetic NdCo₅ layers (canting angles between 65° and 22°), and to a NdCo₅ film covered with permalloy. Interestingly, permalloy induces a 43° rotation of Co magnetization towards surface normal. Our method allows identifying complex topological defects (merons or ½ skyrmions) in a NdCo₅ film that are only partially replicated by the permalloy overlayer. These results open possibilities for the characterization of deeply buried magnetic topological defects, nanostructures and devices.

Epithelial tissues are composed of layers of tightly connected cells shaped into complex three-dimensional (3D) structures such as cysts, tubules, or invaginations. These complex 3D structures are important for organ-specific functions and often create biochemical gradients that guide cell positioning and compartmentalization within the organ. One of the main functions of epithelia is to act as physical barriers that protect the underlying tissues from external insults. In vitro, epithelial barriers are usually mimicked by oversimplified models based on cell lines grown as monolayers on flat surfaces. While useful to answer certain questions, these models cannot fully capture the in vivo organ physiology and often yield poor predictions. In order to progress further in basic and translational research, disease modeling, drug discovery, and regenerative medicine, it is essential to advance the development of new in vitro predictive models of epithelial tissues that are capable of representing the in vivo-like structures and organ functionality more accurately. Here, we review current strategies for obtaining biomimetic systems in the form of advanced in vitro models that allow for more reliable and safer preclinical tests. The current state of the art and potential applications of self-organized cell-based systems, organ-on-a-chip devices that incorporate sensors and monitoring capabilities, as well as microfabrication techniques including bioprinting and photolithography, are discussed. These techniques could be combined to help provide highly predictive drug tests for patient-specific conditions in the near future.