Light-driven phase transition of diffractive optical elements based on liquid crystal elastomers.

Diffractive optical element is advantageous for miniaturization, arraying and integration of optical systems. They have been widely used in beam shaping, diffractive imaging, generating beam arrays, spectral optimization and other aspects. Currently, the vast majority of diffractive optics are not tunable. This limits the applicability and functionality of these devices. Here we report a tunable diffractive optical element controlled by light in the visible band. The diffractive optical element consists of a square gold microarray deposited on a deformable substrate. The substrate is made of a liquid crystal elastomer. When pumped by a 532 nm laser, the substrate is deformed to change the crystal lattice. This changes the far-field diffraction pattern of the device. The proposed concept establishes a light-controlled soft platform with great potential for tunable/reconfigurable photonic devices, such as filters, couplers, holograms and structural color displays.

Responsive Liquid Crystal Network Microstructures with Customized Shapes and Predetermined Morphing for Adaptive Soft Micro-Optics.

Stimuli-responsive materials have garnered substantial interest in recent years, particularly liquid crystal networks (LCNs) with sophisticatedly designed structures and morphing capabilities. Extensive efforts have been devoted to LCN structural designs spanning from two-dimensional (2D) to three-dimensional (3D) configurations and their intricate morphing behaviors through designed alignment. However, achieving microscale structures and large-area preparation necessitates the development of novel techniques capable of facilely fabricating LCN microstructures with precise control over both overall shape and alignment, enabling a 3D-to-3D shape change. Herein, a simple and cost-effective in-cell soft lithography (ICSL) technique is proposed to create LCN microstructures with customized shapes and predesigned morphing. The ICSL technique involves two sequential steps: fabricating the desired microstructure as the template by using the photopolymerization-induced phase separation (PIPS) method and reproducing the LCN microstructures through templating. Meanwhile, surface anchoring is employed to design and achieve molecular alignment, accommodating different deformation modes. With the proposed ICSL technique, cylindrical and spherical microlens arrays (CMLAs and SMLAs) have been successfully fabricated with stimulus-driven polarization-dependent focusing effects. This technique offers distinct advantages including high customizability, large-area production, and cost-effectiveness, which pave a new avenue for extensive applications in different fields, exemplified by adaptive soft micro-optics and photonics.

A colorimetric sensor based on Glutathione-AgNPs as peroxidase mimetics for the sensitive detection of Thiamine (Vitamin B1).

A label-free sensing strategy based on the enzyme-mimicking property of Glutathione-Ag nanoparticles (GSH-AgNPs) was demonstrated for colorimetric detection of vitamin B1 (VB1). Firstly, obvious blue color accompanied with an absorption peak at 652 nm was observed due to the high peroxidase-like activity of GSH-AgNPs towards 3,3',5,5'-tetramethylbenzidine (TMB). Then, in the presence of VB1, the mimetic activity of GSH-AgNPs could be strongly restrained, evidenced as a promiment colorimetric change to colorless, which can be used to achieve the visualization detection VB1. Linear relationship between absorbance response and VB1 concentration from 0 to 0.2 µM were obtained. The detection limit was calculated as low as 40 nM. The inhibition reasons were thoroughly discussed. Considering the advantages of rapid response, easy procedure and high selectivity, the proposed method possesses potential application in environment and biological analysis for VB1 detection.