Nanostructured Dielectric Fractals on Resonant Plasmonic Metasurfaces for Selective and Sensitive Optical Sensing of Volatile Compounds

Abstract

Advances in the understanding and fabrication of plasmonic nanostructures have led to a plethora of unprecedented optoelectronic and optochemical applications. Plasmon resonance has found widespread use in efficient optical transducers of refractive index changes in liquids. However, it has proven challenging to translate these achievements to the selective detection of gases, which typically adsorb non-specifically and induce refractive index changes below the detection limit. Here, it's shown that integration of tailored fractals of dielectric TiO nanoparticles on a plasmonic metasurface strongly enhances the interaction between the plasmonic field and volatile organic molecules and provides a means for their selective detection. Notably, this superior optical response is due to the enhancement of the interaction between the dielectric fractals and the plasmonic metasurface for thickness of up to 1.8 μm, much higher than the evanescent plasmonic near-field (≈30 nm) . Optimal dielectric-plasmonic structures allow measurements of changes in the refractive index of the gas mixture down to <8 × 10 at room temperature and selective identification of three exemplary volatile organic compounds. These findings provide a basis for the development of a novel family of dielectric-plasmonic materials with application extending from light harvesting and photocatalysts to contactless sensors for noninvasive medical diagnostics.

High‐Temperature Large‐Scale Self‐Assembly of Highly Faceted Monocrystalline Au Metasurfaces

“…Enhancing the sensitivity of LSPR optical gas sensors has been pursued by many approaches including the integration of catalytic reactive layers, 2D materials, or photonic crystal . Here, to further explore the potential of these highly faceted Au monocrystalline nanoislands, we implement a very recent strategy relying on the nanotexturing of plasmonic metasurfaces with highly porous fractal layers . To this aim, ≈98% porous TiO 2 nanoparticle networks were fabricated on the Au nanoisland surfaces by the aerosol deposition of flame‐made TiO 2 nanoparticles, forming a well‐defined plasmonic–dielectric interface (Figure c,d and Figure S7, Supporting Information).…”

Nanostructured β‐Bi2O3 Fractals on Carbon Fibers for Highly Selective CO2 Electroreduction to Formate

“…[21,22] Additionally, several research fields are starting to employ the excellent flexibility of complex disordered structures that present hierarchical features and self-similar properties repeating at different magnifications, a peculiar characteristic of fractal. [23,24] Aggregates of fractal nanoparticles have widespread applications in various fields of nanotechnology. [24][25][26][27] Their bottom-up hierarchical organization provides a tunable three-dimensional morphology bridging over several lengthscales, from the size of the individual nanoparticles to the micro/macro-scale of the devices.…”

“…[21] Figure S1 shows networks . [23,45] The fractal state of a material is defined by two dimensionless parameters, namely the fractal dimension (D f ) and lacunarity (Λ). [31,46] The first parameter, D f , is essentially a scaling rule, which shows the degree of statistical complexity of a system at different length scales and complies with the power law.…”

Recent Advances in Flexible Field‐Effect Transistors toward Wearable Sensors

“…Pollutions caused by the rapid development of industry have become an urgent problem because the substances not only pollute the environment, but also are detrimental to the health of humans. [164][165][166] It is therefore essential to monitor these polluting substances effectively and accurately. The sensing behavior of chemical sensors generally is based on the interactions between target substances and sensors, including charge transfer, [167][168][169] hydrophobic/hydrophilic interactions, [170,171] dipoledipole interactions, [167,172] capacity variation, [173] and hydrogen bonding.…”