Ammonia, a major water pollutant, enters aquatic environments from various sources, impacting aquatic life with toxic effects and promoting algae growth. Detecting dissolved ammonia is crucial due to health risks and harm to ecosystems. A nanoplasmonic colorimetric sensor was developed, utilizing metallic nanostructures to change color based on ammonia concentrations, providing a simple and affordable real-time analysis method. The sensor uses aluminum and aluminum oxide, avoiding toxic chemicals. A smartphone application was also developed as a robust protocol for quantifying ammonia in aqueous solutions, eliminating the need for optical instruments and facilitating on-site monitoring.
Commercial paints have issues with toxicity, environmental instability, and low resolution. Researchers have proposed nanostructured materials as eco-friendly coloration alternatives. However, existing demonstrations face challenges such as sensitivity to angles, polarizations, limited saturation, and impractical industrial integration. We present a self-standing structural coloration approach that exploits plasmonic resonances to produce a comprehensive color range, providing a vivid and rich palette, with angle and polarization independence. Our ultralight paint, weighing only 0.4 g/m2, is fabricated through large-scale techniques, bridging the gap to real-world industrial applications for non-toxic, fade-resistant, and environmentally friendly structural color.
Virtual Reality (VR) devices present challenges in terms of vergence-accommodation conflict that lead to visual fatigue for the user over time. Fast switchable liquid crystal (LC) lenses which access multiple focal planes can help to overcome this challenge. The response time for Nematic liquid crystals (NLC) is in the millisecond range, while that of ferroelectric liquid crystals (FLC) in the microsecond order. In this paper we look at recent advances in fast switchable liquid crystal lenses using NLC, FLC or both, compare their design and properties with competing technologies. A discussion on the limitations of each design and technology have also been included.
Several nanoengineered materials have been proposed as potential alternatives to chemical colorants. Although they are non-toxic and stable, they suffer from severe angle and polarization sensitivity, lack of saturation, limited color-palette, and are impractical to integrate with industrial standards. Here, we present an approach to structural coloration that avoids these limitations by exploiting the strong hybridization of localized and cavity modes of a layer of self-assembled plasmonic nanoparticles in the proximity of a mirror. Our approach offers a versatile platform for environmental-friendly, large-scale, and low-cost paint solution that bridges the gap from proof-of-concept science to real-world industrial applications.
Recently, several nanostructures have been proposed as a route for structural coloration. However, these demonstrations suffer from severe angle and polarization sensitivity and are impractical to integrate with industrial standards. Here, we present an approach to structural coloration that exploits the strong hybridization of localized and cavity modes of a layer of self-assembled plasmonic nanoparticles in near-field proximity to a mirror. Our approach offers a large-scale and low-cost process, that can be applied to different types of substrates offering a highly versatile colorization solution that can be exploited for biosensing, displays, or as-is for producing structural color paint.
Recent disclosures on subwavelength plasmonic crystals, like the potential excitation of a pair of coexisting wave-fields
with opposite refraction, only can be understood by considering two dispersion branches with completely
different features that characterize the metamaterial. One branch gives elliptic-like dispersion and the other
provides hyperbolic-like dispersion. However the effective medium approximation, also known as Rytov approximation,
is not consistent with both curves simultaneously. We follow an approach leading to a single curve that
allows a complete description of both diffraction behaviors concurrently. Importantly only two parameters of the
closed curve, together with the lattice period, fulfill such a complete picture. In addition, our semi-analytical
approach may include more general situations straightforwardly.
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