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Here, we report an electrochemiluminescence (ECL)-based approach for imaging of local photoelectrochemical processes on hematite in a spatially and temporally controlled manner. The local processes were guided by flexible and dynamic light illumination, not requiring any prepatterned conductive features or photomasks, with a digital micromirror device (DMD). The imaging approach was based on light-addressable electrochemical reactions on hematite, resulting in photoinduced ECL emission for spatiotemporally resolved imaging of photoelectrochemical processes selectively guided by light illumination. After clarifying the capability of hematite as a photosensitive electrode, we validated that the illuminated hematite exhibited stable light-guided ECL emission in correspondence with the illuminated area, with a spatial resolution of 0.8 µm and a temporal resolution of 1 µs, even over a long period of 6 h. More importantly, this study exemplified the simple yet effective ECL-based approach for electrochemical visualization of local photoelectrochemical processes guided by flexible and dynamic adjustment of light illumination in a spatiotemporally controlled way.
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Sustainability, humidity sensing and product origin are important features of food packaging. While waste generated from labelling and packaging causes environmental destruction, humidity can result in food spoilage during delivery and counterfeit-prone labelling undermines consumer trust. Here we introduce a food label based on a water-soluble nanocomposite ink with a high refractive index that addresses these issues. By patterning the nanocomposite ink using nanoimprint lithography, the resultant metasurface shows bright and vivid structural colours. This method makes it possible to quickly and inexpensively create patterns on large surfaces. A QR code is also developed that can provide up-to-date information on food products. Microprinting hidden in the QR code protects against counterfeiting, cannot be physically detached or replicated and may be used as a humidity indicator. Our proposed food label can reduce waste while ensuring customers receive accurate product information.
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Rotulagem de Alimentos , Embalagem de Alimentos , Água , Embalagem de Alimentos/normas , Rotulagem de Alimentos/legislação & jurisprudência , Água/química , Nanocompostos/química , Tinta , Solubilidade , Umidade , Fraude/prevenção & controleRESUMO
Nanoimprint lithography (NIL) has been utilized to address the manufacturing challenges of high cost and low throughput for optical metasurfaces. To overcome the limitations inherent in conventional imprint resins characterized by a low refractive index (n), high-n nanocomposites have been introduced to directly serve as meta-atoms. However, comprehensive research on these nanocomposites is notably lacking. In this study, we focus on the composition of high-n zirconium dioxide (ZrO2) nanoparticle (NP) concentration and solvents used to produce ultraviolet (UV) metaholograms and quantify the transfer fidelity by the measured conversion efficiency. The utilization of 80 wt% ZrO2 NPs in MIBK, MEK, and acetone results in conversion efficiencies of 62.3%, 51.4%, and 61.5%, respectively, at a wavelength of 325 nm. The analysis of the solvent composition and NP concentration can further enhance the manufacturing capabilities of high-n nanocomposites in NIL, enabling potential practical use of optical metasurfaces.
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Metasurfaces are flat arrays of nanostructures that allow exquisite control of phase and amplitude of incident light. Although metasurfaces offer new active element for both fundamental science and applications, the challenge still remains to overcome their low information capacity and passive nature. Here, by integrating an inverse-designed-metasurface with oblique helicoidal cholesteric liquid crystal (ChOH), simultaneous spatial and spectral tunable metasurfaces with a high information capacity for dynamic hyperspectral holography, are demonstrated. The inverse design facilitates a single-phase map encoding of ten independent holographic images at different wavelengths. ChOH provides precise spectral modulation with narrow bandwidth and wide tunable regime in response to programmed stimuli, thus enabling dynamic switching of the multicolor holography. The results provide simple and generalizable principles for the rational design of interactive metasurfaces that will find numerous applications, including security platform.
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Metasurfaces have recently risen to prominence in optical research, providing unique functionalities that can be used for imaging, beam forming, holography, polarimetry, and many more, while keeping device dimensions small. Despite the fact that a vast range of basic metasurface designs has already been thoroughly studied in the literature, the number of metasurface-related papers is still growing at a rapid pace, as metasurface research is now spreading to adjacent fields, including computational imaging, augmented and virtual reality, automotive, display, biosensing, nonlinear, quantum and topological optics, optical computing, and more. At the same time, the ability of metasurfaces to perform optical functions in much more compact optical systems has triggered strong and constantly growing interest from various industries that greatly benefit from the availability of miniaturized, highly functional, and efficient optical components that can be integrated in optoelectronic systems at low cost. This creates a truly unique opportunity for the field of metasurfaces to make both a scientific and an industrial impact. The goal of this Roadmap is to mark this "golden age" of metasurface research and define future directions to encourage scientists and engineers to drive research and development in the field of metasurfaces toward both scientific excellence and broad industrial adoption.
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Angle-dependent next-generation displays have potential applications in 3D stereoscopic and head-mounted displays, image combiners, and encryption for augmented reality (AR) and security. Metasurfaces enable such exceptional functionalities with groundbreaking achievements in efficient displays over the past decades. However, limitations in angular dispersion control make them unfit for numerous nanophotonic applications. Here, we propose a spin-selective angle-dependent all-dielectric metasurface with a unique design strategy to manifest distinct phase information at different incident angles of light. As a proof of concept, the phase masks of two images are encoded into the metasurface and projected at the desired focal plane under different angles of left circularly polarized (LCP) light. Specifically, the proposed multifunctional metasurface generates two distinct holographic images under LCP illumination at angles of +35 and -35°. The presented holographic displays may provide a feasible route toward multifunctional meta-devices for potential AR displays, encrypted imaging, and information storage applications.
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In this work, we report a bipolar electrode (BPE) array system with self-driven optical readouts of the faradic current flowing through the BPEs. The BPE array system is based on the spontaneous redox reactions that are respectively occurring at opposite poles of the BPEs with appropriate electrocatalysts on the poles; this system is analogous to one consisting of galvanic electrochemical cells. The galvanic BPE array system operates in a self-powered mode that requires there to be neither a direct electrical connection nor external electrical polarization to each BPE. Importantly, the appropriate electrocatalysts on the poles play a critical role in the galvanic BPE array system to induce the spontaneous redox reactions occurring at the poles of BPEs. Moreover, the galvanic BPE array system provides self-driven optical readouts, including fluorometric and colorimetric ones, to report the faradaic current resulting from the spontaneous redox reactions on the BPE poles. Based on the unique benefits that the galvanic BPE array system has over conventional BPEs, we demonstrated the promising potential of galvanic BPE arrays for the simple yet rapid and quantitative screening of electrocatalysts for the oxygen reduction reaction as well as sensitive sensing of H2O2 in parallel.
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Técnicas Biossensoriais , Peróxido de Hidrogênio , Técnicas Biossensoriais/métodos , Eletrodos , Fluorometria , OxirreduçãoRESUMO
Donor-acceptor (D-A) type molecules with a skeleton consisting of a dimethylaminonaphthalene donor and an oxazaborine acceptor were designed as efficient electrochemiluminescence (ECL) luminophores with tunable intramolecular charge transfer (ICT). The D-A ECL luminophores demonstrated that the ICT characteristics play a critical role in the electrochemistry and ECL of luminophores in the presence of tri-n-propylamine, which was rationalised experimentally and computationally. Furthemore, dual-peaked ECL-potential behaviours of the luminophores were rationalised using two competitive pathway ECL mechanisms, elucidated through the use of spooling ECL spectroscopy.
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The imaging of microscopic biological samples faces numerous difficulties due to their small feature sizes and low-amplitude contrast. Metalenses have shown great promise in bioimaging as they have access to the complete complex information, which, alongside their extremely small and compact footprint and potential to integrate multiple functionalities into a single device, allow for miniaturized microscopy with exceptional features. Here, we design and experimentally realize a dual-mode metalens integrated with a liquid crystal cell that can be electrically switched between bright-field and edge-enhanced imaging on the millisecond scale. We combine the concepts of geometric and propagation phase to design the dual-mode metalens and physically encode the required phase profiles using hydrogenated amorphous silicon for operation at visible wavelengths. The two distinct metalens phase profiles include (1) a conventional hyperbolic metalens for bright-field imaging and (2) a spiral metalens with a topological charge of +1 for edge-enhanced imaging. We demonstrate the focusing and vortex generation ability of the metalens under different states of circular polarization and prove its use for biological imaging. This work proves a method for in vivo observation and monitoring of the cell response and drug screening within a compact form factor.
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Metasurfaces have been continuously garnering attention in both scientific and industrial fields, owing to their unprecedented wavefront manipulation capabilities using arranged subwavelength artificial structures. To date, research has mainly focused on the full control of electromagnetic characteristics, including polarization, phase, amplitude, and even frequencies. Consequently, versatile possibilities of electromagnetic wave control have been achieved, yielding practical optical components such as metalenses, beam-steerers, metaholograms, and sensors. Current research is now focused on integrating the aforementioned metasurfaces with other standard optical components (e.g., light-emitting diodes, charged-coupled devices, micro-electro-mechanical systems, liquid crystals, heaters, refractive optical elements, planar waveguides, optical fibers, etc.) for commercialization with miniaturization trends of optical devices. Herein, this review describes and classifies metasurface-integrated optical components, and subsequently discusses their promising applications with metasurface-integrated optical platforms including those of augmented/virtual reality, light detection and ranging, and sensors. In conclusion, this review presents several challenges and prospects that are prevalent in the field in order to accelerate the commercialization of metasurfaces-integrated optical platforms.
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Wearable displays or head-mounted displays (HMDs) have the ability to create a virtual image in the field of view of one or both eyes. Such displays constitute the main platform for numerous virtual reality (VR)- and augmented reality (AR)-based applications. Meta-holographic displays integrated with AR technology have potential applications in the advertising, media, and healthcare sectors. In the previous decade, dielectric metasurfaces emerged as a suitable choice for designing compact devices for highly efficient displays. However, the small conversion efficiency, narrow bandwidth, and costly fabrication procedures limit the device's functionalities. Here, we proposed a spin-isolated dielectric multi-functional metasurface operating at broadband optical wavelengths with high transmission efficiency in the ultraviolet (UV) and visible (Vis) regimes. The proposed metasurface comprised silicon nitride (Si3N4)-based meta-atoms with high bandgap, i.e., â¼ 5.9 eV, and encoded two holographic phase profiles. Previously, the multiple pieces of holographic information incorporated in the metasurfaces using interleaved and layer stacking techniques resulted in noisy and low-efficiency outputs. A single planar metasurface integrated with a liquid crystal was demonstrated numerically and experimentally in the current work to validate the spin-isolated dynamic UV-Vis holographic information at broadband wavelengths. In our opinion, the proposed metasurface can have promising applications in healthcare, optical security encryption, anti-counterfeiting, and UV-Vis nanophotonics.
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Obtaining single-molecular-level fingerprints of biomolecules and electron-transfer dynamic imaging in living cells are critically demanded in postgenomic life sciences and medicine. However, the possible solution called plasmonic resonance energy transfer (PRET) spectroscopy remains challenging due to the fixed scattering spectrum of a plasmonic nanoparticle and limited multiplexing. Here, multiplexed metasurfaces-driven PRET hyperspectral imaging, to probe biological light-matter interactions, is reported. Pixelated metasurfaces with engineered scattering spectra are first designed over the entire visible range by the precision nanoengineering of gap plasmon and grating effects of metasurface clusters. Pixelated metasurfaces are created and their full dark-field coloration is optically characterized with visible color palettes and high-resolution color printings of the art pieces. Furthermore, three different biomolecules (i.e., chlorophyll a, chlorophyll b, and cytochrome c) are applied on metasurfaces for color palettes to obtain selective molecular fingerprint imaging due to the unique biological light-matter interactions with application-specific biomedical metasurfaces. This metasurface-driven PRET hyperspectral imaging will open up a new path for multiplexed real-time molecular sensing and imaging methods.
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Citocromos c , Imageamento Hiperespectral , Clorofila A , Transporte de Elétrons , Transferência de EnergiaRESUMO
A single-step printable platform for ultraviolet (UV) metasurfaces is introduced to overcome both the scarcity of low-loss UV materials and manufacturing limitations of high cost and low throughput. By dispersing zirconium dioxide (ZrO2) nanoparticles in a UV-curable resin, ZrO2 nanoparticle-embedded-resin (nano-PER) is developed as a printable material which has a high refractive index and low extinction coefficient from near-UV to deep-UV. In ZrO2 nano-PER, the UV-curable resin enables direct pattern transfer and ZrO2 nanoparticles increase the refractive index of the composite while maintaining a large bandgap. With this concept, UV metasurfaces can be fabricated in a single step by nanoimprint lithography. As a proof of concept, UV metaholograms operating in near-UV and deep-UV are experimentally demonstrated with vivid and clear holographic images. The proposed method enables repeat and rapid manufacturing of UV metasurfaces, and thus will bring UV metasurfaces more close to real life.
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Metalenses are attractive alternatives to conventional bulky refractive lenses owing to their superior light-modulating performance and sub-micrometre-scale thicknesses; however, limitations in existing fabrication techniques, including high cost, low throughput and small patterning area, have hindered their mass production. Here we demonstrate low-cost and high-throughput mass production of large-aperture visible metalenses using deep-ultraviolet argon fluoride immersion lithography and wafer-scale nanoimprint lithography. Once a 12â³ master stamp is imprinted, hundreds of centimetre-scale metalenses can be fabricated using a thinly coated high-index film to enhance light confinement, resulting in a substantial increase in conversion efficiency. As a proof of concept, an ultrathin virtual reality device created with the printed metalens demonstrates its potential towards the scalable manufacturing of metaphotonic devices.
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Metasurfaces have shown remarkable potential to manipulate many of light's intrinsic properties, such as phase, amplitude, and polarization. Recent advancements in nanofabrication technologies and persistent efforts from the research community result in the realization of highly efficient, broadband, and multifunctional metasurfaces. Simultaneous control of these characteristics in a single-layered metasurface will be an apparent technological extension. Here, we demonstrate a broadband multifunctional metasurface platform with the unprecedented ability to independently control the phase profile for two orthogonal polarization states of incident light over dual-wavelength spectra (ultraviolet to visible). In this work, multiple single-layered metasurfaces composed of bandgap-engineered silicon nitride nanoantennas are designed, fabricated, and optically characterized to demonstrate broadband multifunctional light manipulation ability, including structured beam generation and meta-interferometer implementation. We envision the presented metasurface platform opening new avenues for broadband multifunctional applications including ultraviolet-visible spectroscopy, spatially modulated illumination microscopy, optical data storage, and information encoding.
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Metasurface-generated holography has emerged as a promising route for fully reproducing vivid scenes by manipulating the optical properties of light using ultra-compact devices. However, achieving multiple holographic images using a single metasurface is still difficult due to the capacity limit of a single meta-atom. In this work, an inverse design method based on gradient-descent optimization is presented to encode multiple pieces of holographic information into a single metasurface. The proposed method allows the inverse design of single-cell metasurfaces without the need for complex meta-atom design strategies, facilitating high-throughput fabrication using broadband low-loss materials. By exploiting the proposed design method, both multiplane red-green-blue (RGB) color and three-dimensional (3D) holograms are designed and experimentally demonstrated. Multiplane RGB color holograms with nine distinct holograms are achieved, which demonstrate the state-of-the-art data capacity of a phase-only metasurface. The first experimental demonstration of metasurface-generated 3D holograms with completely independent and distinct images in each plane is also presented. The current research findings provide a viable route for practical metasurface-generated holography by demonstrating the high-density holography produced by a single metasurface. It is expected to ultimately lead to optical storage, display, and full-color imaging applications.
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Direct imaging of electrochemical processes on electrode surfaces is a central part of understanding spatially heterogeneous electrochemical processes on the surfaces. Herein, we report a strategy for the spatially resolved imaging of local faradaic processes on nanoscale electrochemical interfaces. This strategy is based on fluorescence lifetime imaging microscopy (FLIM) with the use of Amplex Red as a fluorogenic redox probe. After verifying the capability of Amplex Red for fluorescence lifetime imaging, we demonstrated the turn-on FLIM-based imaging of faradaic processes on the electrochemical interfaces of different dimensions. In particular, we achieved spatially resolved visualization of the local electrochemical processes occurring on even nanopore electrode arrays as well as conventional microelectrodes, including disk-shaped ultramicroelectrodes and interdigitated array microelectrodes.
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Nanoporos , Oxirredução , Microeletrodos , Microscopia de FluorescênciaRESUMO
Multi-functional metasurfaces have attracted great attention due to the significant possibilities to realize highly integrated and ultra-compact meta-devices. Merging nano-printing and holographic information multiplexing is one of the effective ways to achieve multi-functionality, and such a merger can increase the information encoding capacity. However, the current approaches rely on stacking layers and interleaving, where multiple resonators effectively combine different functionalities on the cost of efficiency, design complexity, and challenging fabrication. To address such challenges, a single meta-nanoresonator-based tri-functional metasurface is proposed by combining the geometric phase-based spin-decoupling and Malus's law intensity modulation. The proposed strategy effectively improves information capacity owing to the orientation degeneracy of spin-decoupling rather than layer stacking or super-cell designs. To validate the proposed strategy, a metasurface demonstrating two helicity-dependent holographic outputs is presented in far-field, whereas a continuous nano-printing image is in near-field. It is also employed on CMOS-compatible and cost-effective hydrogen amorphous silicon providing transparent responses for the whole visible band. As a result, the proposed metasurface has high transmission efficiency in the visible regime and verifies the design strategy without adding extra complexities to conventional nano-pillar geometry. Therefore, the proposed metasurface opens new avenues in multi-functional meta-devices design and has promising applications in anti-counterfeiting, optical storage and displays.â.
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Three types of carbon dots (CDs) are synthesized from isomers of phenylenediamine to develop multicolor nanomaterials with low toxicity, high stability, and high quantum yield. The distinctive electronic structures of CDs lead to the characteristic optical transitions, such as three colors of blue, green, and red, which are primarily attributed to the difference in configurations, despite the similar basic structures of conjugated systems. The excitation-independent emission and the single exponential decay of CDs indicate the single chromophore-like nature in each type of CD. In addition, the two-photon luminescence of CDs exhibits a comparable shape and time profile to the typical photoluminescence with high photostability. Although the surface-related defect states are observed by intragap excitation, the contribution of defect states is barely observed in the emission profile upon band gap excitation. Consequently, the controllability of optical transitions in CDs enhances the potential of tunable multicolor nanomaterials for various applications as alternatives to quantum dots containing toxic elements.