Fabrication of Chiral Liquid Crystal Pinwheel Arrays Through Capillarity-Assisted Particle Assembly.

Nucleation of the phase transition in liquid crystals (LCs) is influenced by elastic distortions around topological defects. While conventional studies have focused on isotropic-LC transitions upon cooling, nucleation in chiral LCs is investigated using colloidal arrays produced by capillarity-assisted particle assembly (CAPA) upon heating to spatially control the nucleation of the isotropic phase rather than that of the LC phase, enabling the fabrication of chiral pinwheel arrays. Optical analysis and Landau-de Gennes simulations reveal that pinwheel arrays arise from the interplay of LC chirality, planar anchoring conditions at the isotropic-LC boundary, and boojum defects on the particles.

Multiplex Optical Unclonable Functions: Advances and Perspectives in Optics and Photonics for Hardware Security.

With the accelerating expansion of connectivity, the need for advanced cyber-physical security technologies that bridge the digital and physical worlds is becoming more crucial than ever. Physically unclonable functions (PUFs) leveraging nanotechnologies and photonic technologies are emerging as practical and deployable hardware security solutions that go beyond software-based hardware security. Optics- and photonics-based PUFs (often referred to as optical PUFs) offer a range of characteristics beneficial to multiplex strategies that incorporate multilevel and multimodal approaches, based on their fundamental optical and photonic properties.

Reconfigurable Liquid Crystal-Based Physical Unclonable Function Integrating Optical and Electrical Responses.

Physical unclonable functions (PUFs)-a hardware-based security device using randomness-have evolved from basic integrated circuit designs to advanced systems using diverse materials and mechanisms. However, most PUFs are limited by single-factor challenges and fixed key generation, making them vulnerable to brute-force attacks. A reconfigurable and multidimensional liquid crystal (LC)-based PUF is presented integrated into an organic field-effect transistor (OFET) to address limitations.

Pixelated Physical Unclonable Functions through Capillarity-Assisted Particle Assembly.

Recent years have shown the need for trustworthy, unclonable, and durable tokens as proof of authenticity for a large variety of products to combat the economic cost of counterfeits. An excellent solution is physical unclonable functions (PUFs), which are intrinsically random objects that cannot be recreated, even if illegitimate manufacturers have access to the same methods. We propose a robust and simple way to make pixelated PUFs through the deposition of a random mixture of fluorescent colloids in a predetermined lattice using capillarity-assisted particle assembly.

Controlling liquid crystal boojum defects on fixed microparticle arrays via capillarity-assisted particles assembly.

Hypothesis: Colloidal particles in nematic liquid crystals (LCs) are of high interest for self-assembly of soft matter systems. When two free particles approach within a uniaxially-oriented nematic LC, an elastic force is generated due to the distorted nematic director configuration around them, allowing particles to self-assemble by an attractive force. We hypothesize that if particles are immobilized, repulsive forces emerge instead, causing the deflection of the interacting defects to compensate for the energy increase.

Hierarchically Fabricated Amyloid Fibers Evaporation-Induced Self-Assembly.

Multiscale hierarchical nano- and microstructures of amyloid fibrils are fabricated by evaporation-induced self-assembly combined with topographic surface patterning techniques. The continuous stick-and-slip motion induces uniaxial alignment of amyloid fibrils characterized by high orientational order during the drying process. The optical textures of the resultant amyloid aggregates are directly observed by polarized optical microscopy (POM) and atomic force microscopy (AFM).

Chiral Optoelectronic Functionalities DNA-Organic Semiconductor Complex.

We fabricate the bio-organic field-effect transistor (BOFET) with the DNA-perylene diimide (PDI) complex, which shows unusual chiroptical and electrical functionalities. DNA is used as the chirality-inducing scaffold and the charge-injection layer. The shear-oriented film of the DNA-PDI complex shows how the large-area periodic molecular orientation and the charge transport are related, generating drastically different optoelectronic properties at each DNA/PDI concentration.

Fabrication of Bilayer Dichroic Films Using Liquid Crystal Materials for Multiplex Applications.

A bilayer dichroic-doped liquid crystal (BDLC) film is fabricated via the uniaxial alignment method and a photopolymerization process. It is found to be useful in dichroic color filters, dual-mode circular polarizers, and chirality detectors. Two kinds of dichroic films with different absorbing wavelengths are cross-stacked to show various colors and contrasts depending on the polarization direction of the incident linearly polarized light, which is comparable with the conventional single-layer dichroic dye-doped (SDLC) film that only shows the contrast difference.