Disordered-nanoparticle–based etalon for ultrafast humidity-responsive colorimetric sensors and anti-counterfeiting displays

Abstract

The development of real-time and sensitive humidity sensors is in great demand from smart home automation and modern public health. We hereby proposed an ultrafast and full-color colorimetric humidity sensor that consists of chitosan hydrogel sandwiched by a disordered metal nanoparticle layer and reflecting substrate. This hydrogel-based resonator changes its resonant frequency to external humidity conditions because the chitosan hydrogels are swollen under wet state and contracted under dry state. The response time of the sensor is ~10 4 faster than that of the conventional Fabry-Pérot design. The origins of fast gas permeation are membrane pores created by gaps between the metal nanoparticles. Such instantaneous and tunable response of a new hydrogel resonator is then exploited for colorimetric sensors, anti-counterfeiting applications, and high-resolution displays.

Novel Spin‐Decoupling Strategy in Liquid Crystal‐Integrated Metasurfaces for Interactive Metadisplays

“…We believe that the proposed designing technique is highly efficient for the practical realization of CMOS-compatible multifunctional devices for touch-sensitive interactive displays and safety labeling applications. [48][49][50]…”

A review of tunable photonics: Optically active materials and applications from visible to terahertz

“…Compared to the traditional dyes/pigments, structural coloration has great potential due to its fine tunability, sustainability, and durability. Several strategies for high color purities and design rules have been successfully demonstrated based on the photonic crystals, plasmonic nanostructure, and thin-film interferometer ( Jung et al., 2022 ; Kim et al., 2019a , 2019b ; Ko et al., 2022 ; Lee et al., 2022 ). The resonance wavelength and the associated plasmonic color are determined by parameters including structural dimension ( Kim et al., 2020c ), optical constant ( Ko et al., 2020 ), surrounding medium ( Yoo et al., 2020b ), and arrangement of photonic structure ( Fu et al., 2018 ).…”

“…As M. L. Brongersma group presented futuristic display with 10000 pixels per inch (PPI) based on the meta-mirrors ( Joo et al., 2020 ), the ultrahigh resolution colored display becomes feasible. Recently, colored display with etalon structure based on the swelling materials shows advanced resolution (∼12,000 PPI); however, pixel-by-pixel control with fast response is still limited ( Jung et al., 2022 ). Therefore, the active materials, which could be scaled down ( e.g.…”

Self-assembled pagoda-like nanostructure-induced vertically stacked split-ring resonators for polarization-sensitive dichroic responses

“…However, no natural materials have the required electromagnetic properties, such as strong artificial chirality [5][6][7][8], hyperbolic dispersion [9], negative magnetic permeability [10], and negative refractive index [11]. To achieve such extraordinary electromagnetic properties, plasmonic metamaterials, or the artificially manufactured metallic structures with unit structures much smaller than the wavelength of light, have been actively researched [12][13][14]. Negative refractive index has been reported from stacked crescent-shaped structures in the broadband wavelength regime [15], and from two-dimensional perforated metaldielectric stacks with a thickness much larger than the free-space wavelength [16].…”