Nanoring Arrays Research Articles

Fingerprinting Magnetic States In Interconnected Nanoring Arrays via Spin Wave Spectra

Fingerprinting Magnetic States In Interconnected Nanoring Arrays via Spin Wave Spectra

SERS Analysis Platform Based on Aptamer Recognition-Release Strategy for Efficient and Sensitive Diagnosis of Colorectal Precancerous Lesions.

Colorectal cancer (CRC) has become a significant global public health challenge, demanding immediate attention due to its high incidence and mortality rates. Regular CRC screening is essential for the early detection of precancerous lesions and CRC. : We developed a novel surface-enhanced Raman scattering (SERS) analysis platform that employs high-throughput microarray chips as carriers and Au/SnO2 nanoring arrays (Au/SnO2 NRAs) as substrates. This platform utilizes an aptamer recognition-release strategy to achieve efficient and sensitive detection of protein tumor markers. In the detection process, the strong affinity and high specificity between the aptamer and the target protein result in competitive replacement of the SERS nanoprobes originally bound to the substrate surface. As a result, the SERS nanoprobes carrying Raman reporter genes are dislodged, leading to a reduction in the SERS signal intensity. The platform demonstrated excellent detection performance, with rapid detection completed within 15minutes and limits of detection (LOD) as low as 6.2×10-12 g/mL for hnRNP A1 and 6.51×10-12 g/mL for S100P. Clinical samples analyzed using the SERS platform showed high consistency with enzyme-linked immunosorbent assay (ELISA) results. This platform offers strong support for the early detection, risk assessment, and treatment monitoring of colorectal cancer precancerous lesions, with broad potential for clinical applications.

Exploring physical and digital architectures in magnetic nanoring array reservoir computers

Physical reservoir computing (RC) is a machine learning technique that is ideal for processing of time dependent data series. It is also uniquely well-aligned to in materio computing realisations that allow the inherent memory and non-linear responses of functional materials to be directly exploited for computation. We have previously shown that square arrays of interconnected magnetic nanorings are attractive candidates for in materio RC, and experimentally demonstrated their strong performance in a range of benchmark tasks (Dawidek et al 2021 Adv. Funct. Mater. 31 2008389, Vidamour et al 2022 Nanotechnology 33 485203, Vidamour et al 2023 Commun. Phys. 6 230). Here, we extend these studies to other lattice arrangements of rings, including trigonal and Kagome grids, to explore how these affect both the magnetic behaviours of the arrays, and their computational properties. We show that while lattice geometry substantially affects the microstate behaviour of the arrays, these differences manifest less profoundly when averaging magnetic behaviour across the arrays. Consequently the computational properties (as measured using task agnostic metrics) of devices with a single electrical readout are found to be only subtly different, with the approach used to time-multiplex data into and out of the arrays having a stronger effect on properties than the lattice geometry. However, we also find that hybrid reservoirs that combine the outputs from arrays with different lattice geometries show enhanced computational properties compared to any single array.

Achieving high sensitivity by adding rings to a plasmonic metasurface with nano-holes

This report demonstrates a subwavelength plasmonic metasurface for a refractive index sensor at near-infrared (NIR) wavelengths. This sensor includes a two-dimensional periodic array of gold nano-rings and nano-holes in a gold film. The structure's potential for high-sensitivity sensing in reflection configuration has been demonstrated. We use a TiN layer in this structure. It prevents light transmission from the resonators, making the transmission spectrum near zero and causing a deeper reflection dip. This sensor can be suitable for biosensing applications like poliovirus sensing. Generally, high sensitivity is obtained for poliovirus of over 817 nm/RIU. It is shown that making ledges around nano-holes increases the resonance wavelength shift and, therefore, the sensitivity by more than 33 times.

Fabrication of Large-Area Ordered Au Nano-Ring Arrays for the Electrochemical Removal and Sensing of Rhodamine 6G Molecules

To understand the formation process of ordered Au nano-ring arrays (NRA), a series of factors—including etchant gas and flow rate, chamber pressure and RF power—were systematically studied and a set of optimum parameters were deduced to fabricate this interesting structure. With plenty of active sites previously reported, a new role of ordered Au NRA is unlocked in this work. The ordered Au NRA could perform the electrochemical removal of rhodamine 6G (R-6G) at a high concentration in seawater within 12 min and complete discoloration within 9 min, which demonstrates ~7 times efficiency improvement from previous studies. The nanostructured surface also makes the ordered Au NRA a good substrate material in R-6G sensing using surface-enhanced Raman spectroscopy, which performs with better accuracy than the ultraviolet–visible light technique.

Metasurface cutoff perfect absorber in a solar energy wavelength band.

We report a metasurface cutoff perfect absorber (MCPA) in the solar energy wavelength band based on the double Mie resonances generated from the silicon and gallium arsenide nanoring arrays grown on the Al layer in the solar energy wavelengths. A high average absorption of 0.910 in the absorption band and almost eliminated absorption in the nonabsorption band are realized within only 120nm thick structures. The MCPA is of a sharp cutoff between the absorption and nonabsorption band, whose extinction ratio, extinction difference, and cutoff slope are 9.4dB, 0.8, and 0.0019n m -1, respectively. The proposed MCPA suggests an efficient way to design a solar thermal absorber, which is of great importance in renewable energy, such as for solar thermal applications.

Reconfigurable reservoir computing in a magnetic metamaterial

In-materia reservoir computing (RC) leverages the intrinsic physical responses of functional materials to perform complex computational tasks. Magnetic metamaterials are exciting candidates for RC due to their huge state space, nonlinear emergent dynamics, and non-volatile memory. However, to be suitable for a broad range of tasks, the material system is required to exhibit a broad range of properties, and isolating these behaviours experimentally can often prove difficult. By using an electrically accessible device consisting of an array of interconnected magnetic nanorings- a system shown to exhibit complex emergent dynamics- here we show how reconfiguring the reservoir architecture allows exploitation of different aspects the system’s dynamical behaviours. This is evidenced through state-of-the-art performance in diverse benchmark tasks with very different computational requirements, highlighting the additional computational configurability that can be obtained by altering the input/output architecture around the material system.

Tunable Gold Nanoring Arrays by Electrodeposition

AbstractGold has many exciting properties that justify its use in a wide range of applications. While gold nanoparticles are frequently used, nanorings offer an interesting new geometry. Unfortunately, few technologies exist to fabricate nanorings, which are often created by multistep lithographic methods. Furthermore, nanoring arrays are even more difficult to achieve. Herein, a one‐step, one‐pot electrodeposition method to realize arrays of gold nanorings with tunable parameters is demonstrated. It is shown that the electrodeposition of gold nanoring arrays can be easily achieved when one submerges a water droplet containing HAuCl4 into an oil‐phase containing a quaternary ammonium salt. These conditions allow for the spontaneous emulsification at the water|oil interface. The nanorings can be deposited at the edges of the emulsion droplets that become adsorbed to the electrode. Changing the concentrations of species, submersion time, and electrodeposition parameters allows us to tune relevant parameters of the array of nanorings, including the thickness and size of the rings.

Design of infrared optical absorber using silver nanorings array made by a top-down process

This paper presents the numerical simulation and fabrication of a metasurface composed of silver nanorings with a split-ring gap. These nanostructures can exhibit optically-induced magnetic responses with unique possibilities to control absorption at optical frequencies. The absorption coefficient of the silver nanoring was optimized by performing a parametric study with Finite Difference Time Domain (FDTD) simulations. The absorption and scattering cross sections of the nanostructures are numerically calculated to assess the impact of the inner and outer radii, the thickness and the split-ring gap of one nanoring, as well as the periodicity factor for a group of four nanorings. This showed full control on resonance peaks and absorption enhancement in the near infrared spectral range. The experimental fabrication of this metasurface made of an array of silver nanorings is achieved by e-beam lithography and metallization. Optical characterizations are then carried out and compared to the numerical simulations. In contrast to usual microwave split-ring resonator metasurfaces reported in literature, the present study shows both the realization by a top-down process and modelling performed in the infrared frequency range.

Shape-altering flexible plasmonics of in-situ deformable nanorings

Nanorings (NRs) with their intrinsic cavities have attracted interest as plasmonic nanoparticles for years, due to the uniform electric field enhancement inside the cavity, lower plasmon damping effects and comparatively high refractive index sensitivities. In the present work, we successfully fabricated a series of Au NR arrays on flexible polydimethylsiloxane substrates by taking advantage of state-of-the-art fabrication methods such as electron beam lithography and wet-etching transfer techniques. In-situ optical measurements on these flexible systems are enabled by implementing a homemade micro-stretcher inside an optical reflection spectroscopy setup. The corresponding dark-field spectra of thin-walled NR arrays exhibit a strong shift to longer wavelengths (i.e., ~ 2.85 nm per 1% strain) under polarization perpendicular to the traction, mainly resulting from the increasing shape deformation of the NRs under strain. Moreover, numerical simulations illustrate that the shifting plasmonic mode has a radially-symmetric charge distribution of the bonding mode and is rather sensitive to the tuning of the NRs’ shape as confirmed by a subsequent in-situ scanning electron microscope characterization. These results explore the possibilities of shape-altering flexible plasmonics for nanoparticles with a cavity and indicate potential applications for plasmonic colors and biochemical sensing in future work.Graphical

Upconversion enhancement based on mode hybridization in metamaterial absorber

Upconversion nanoparticles (UCNPs) can be used to harvest near-infrared (NIR) light and convert it into visible light. Although this improves optical device operating spectral range and efficiency, e.g., solar cells, typical UCNPs conversion efficiency is too low for practical devices. In this paper, we utilize mode hybridization to enhance the upconversion emission in a metamaterial absorber, which consists of metallic nanoring arrays, UCNPs and a metal film. Numerical and theoretical analysis results show that the maximum upconversion enhancement factor of 2.5×106 is achieved due to the mixture of gap plasmonic resonance mode and surface lattice resonance mode. Moreover, the electromagnetic field distribution shows that the anti-crossing behavior strongly impacts the mode distribution, making the mode energy contribute to upconversion. The designed metamaterial absorber is a novel approach in enhancing upconversion and promising for solar cells.

Design of broadband high efficiency absorption antenna based on metamaterial nano-ring array

Compared with the traditional solar cells, the nano-optical antenna breaks through the band-gap limitation of semiconductor materials, and provides a new scheme for solar energy collection. In order to solve the problems of complex structure, low efficiency and narrow bandwidth of nano-optical antenna, a novel nano-ring-cylinder based on metamaterials is proposed in this paper. The antenna has an average absorption efficiency of 96.93% in the wide-band absorption range of visible and near-infrared light. First of all, the basic design theory of the antenna was given based on the surface plasma theory. Then, the antenna structure design scheme was determined, the overall structure consists of two layers of metal and an insulating layer formed by Al2O3. Finally, on the basis of the established antenna model, the absorption characteristics were analyzed by simulation. The analysis result shows that the super-absorption ability of the antenna is independent of the polarization of the incident light, and the average absorption ability can be maintained at about 91% when the incident angle is ±60°. The absorption capability of the antenna is mainly due to the synergistic effect of Fabry-Perot resonance and localized surface plasmon resonance enhancement. The conclusion can provide a theoretical guidance for the structural design of nano-optical antenna.

Quantifying the computational capability of a nanomagnetic reservoir computing platform with emergent magnetisation dynamics

Devices based on arrays of interconnected magnetic nano-rings with emergent magnetization dynamics have recently been proposed for use in reservoir computing applications, but for them to be computationally useful it must be possible to optimise their dynamical responses. Here, we use a phenomenological model to demonstrate that such reservoirs can be optimised for classification tasks by tuning hyperparameters that control the scaling and input-rate of data into the system using rotating magnetic fields. We use task-independent metrics to assess the rings’ computational capabilities at each set of these hyperparameters and show how these metrics correlate directly to performance in spoken and written digit recognition tasks. We then show that these metrics, and performance in tasks, can be further improved by expanding the reservoir’s output to include multiple, concurrent measures of the ring arrays’ magnetic states.

Infrared-blocking plasmonic meta-glass for energy-saving passive windows.

Passive windows that can concurrently block infrared radiation while allowing transmission of visible radiation help in significantly reducing global energy usage by cooling and lighting systems deployed in buildings and vehicles. This Letter reports a design of plasmonic "meta-glass" that blocks up to ∼87% of infrared radiation over a spectral window of 750-1800 nm, predominantly responsible for indoor radiative heating, while maintaining an average visible transmission of 60% for providing indoor illumination. Our polarization-independent design comprises a two-dimensional hexagonal array of tungsten nanorings placed on top of a silica glass substrate. By virtue of surface plasmons excitation in the infrared regime, we achieve selective suppression in the transmission spectrum, which is tailorable by adjusting the dimension of the nanorings. The theoretically calculated figure-of-merit indicates that our proposed meta-glass designs outperform some of the recently reported window glass varieties in the literature.

Readily tunable surface plasmon resonances in gold nanoring arrays fabricated using lateral electrodeposition.

Generation and fine-tuning of surface plasmon resonances is a prerequstite for several established and emerging applications such as photovoltaics, photocatalysis, photothermal therapy, surface-enhanced spectroscopy, sensing, superlensing and lasing. We present a low-cost and scalable lateral electrodeposition method for fabrication of high aspect ratio gold nanoring arrays that exhibit multiple surface plasmon resonances in the visible to near-infrared region. Nickel disc arrays of 2 µm size were initially fabricated using maskless lithography and e-beam evaporation. Selective electrodeposition of gold on the lateral surfaces of nickel disc arrays was achieved using a 50 nm SiO2 film as an insulating mask. Growing from miniscule 100 nm wide lateral surfaces of nickel discs, nanorings with height up to 1084 nm could be obtained with their thickness and aspect ratio governed by the duration of electrodeposition. Facile tuning of the number of plasmon resonances, their resonant wavelength and relative intensity is demonstrated with applications in plasmon mediated photocatalysis and surface-enhanced Raman scattering.

Thermally Excited Spin Waves of NiFe Nano-ring Arrays on Anodic Aluminum Oxide Templates

The patterned substrates have been widely developed for various applications in the nanotechnology. In particular, the magnetic ring arrays could be utilized to not only the magnetic devices, such as memories and logics, but also magnetic stealth films using spin wave excitations. In this works, the magnetic switching behaviors and the thermally excited spin wave properties of the NiFe (permalloy) ring arrays on the anodic aluminum oxide template with carbon nanotubes were investigated. With increasing the diameter of the rings, the larger dipole interactions induced the larger coercive field of the array films in the plane directions. At the magnetically saturation conditions, the smaller diameter of the rings produced the single and broad spin wave absorptions due to the isotropic magnetic domains in both the horizontal and the vertical directions. When the size of the ring increased, each component felt different magnetic anisotropy field so that the two spin wave excitation peaks revealed. In terms of the mass production of the magnetic nano-ring arrays on the anodic aluminum oxide template, the various size and the shapes of the magnetic ring patterns could be good candidates for the rf stealth films of the defense industries.

High-performance refractive index sensing system based on multiple Fano resonances in polarization-insensitive metasurface with nanorings.

An optical refractive index sensor is a detection device that can convert changes in the refractive index into detectable optical information. The combination of surface plasmon resonance (SPR) and Fano resonance can improve some key indicators, i. e., sensing sensitivity, figure of merit (FOM), band number, and polarization sensitivity, which are all related to the comprehensive performance for high-precision and multi-band sensing. In our manuscript, we proposed a refractive index sensor composed of a nanoring array and a Fabry-Pérot (F-P) resonant cavity. The coupling of the localized surface plasmon resonances (LSPR) of the nanoring array and the cavity mode of the F-P resonant cavity can produce double Fano resonances. The corresponding sensing sensitivities can reach 621.5 nm/RIU and 906.9 nm/RIU, and the corresponding FOMs can reach 119.7 and 119.0. Then we studied the influence of the structure parameters on the sensitivity and FOM of the sensor through simulation calculation and theoretical analysis and verified the insensitivity of the structure to the polarization of incident light. Our structure has high comprehensive performance, not only polarization insensitivity but also high sensing sensitivity and FOM in both bands, which is more suitable for practical applications.

Observation of magnon–magnon coupling with high cooperativity in Ni80Fe20 cross-shaped nanoring array

We report here an experimental observation of dynamic dipolar coupling induced magnon–magnon coupling and spin wave (SW) mode splitting in Ni80Fe20 cross-shaped nanoring array. Remarkably, we observe an anticrossing feature with minimum frequency gap of 0.96 GHz and the corresponding high cooperativity value of 2.25. Interestingly, splitting of the highest frequency SW mode occurs due to the anisotropic dipolar interactions between the cross nanorings. Furthermore, using micromagnetic simulations we demonstrate that the coupled SW modes propagate longer as opposed to other modes present in this system. Our work paves the way towards integrated hybrid systems-based quantum magnonics and on-chip coherent information transfer.

Au nanoring arrays with tunable morphological features and plasmonic resonances

Gold nanoring arrays are widely applied in various fields benefitting from their localized surface plasmon resonance (LSPR) properties. A key advantage of gold nanoring arrays is that the dipole resonance peak can be systematically tuned by changing the dimensions of gold nanoring arrays. However, most of the currently reported methods for preparing gold nanoring arrays cannot conveniently control the heights of the nanorings at a low cost. Here we introduce a facile method for preparing gold nanoring arrays with tunable plasmonic resonances using colloidal lithography. The dimensions of the nanorings including diameters, lattice constants, even the heights of the nanorings can be conveniently varied. Fourier transform near-infrared (FT-NIR) absorption spectroscopy was used to obtain the plasmonic resonance spectra of the nanoring arrays. All the prepared gold nanoring arrays exhibited a strong NIR or infrared (IR) plasmonic resonance which can be tuned by varying the nanoring dimensions. This versatile method can also be used to fabricate other types of plasmonic nanostructures, such as gold nanocone arrays. The obtained gold nanoring arrays as well as nanocone arrays may have potential applications in surface-enhanced spectroscopy or plasmonic sensing.

Large-Area Fabrication of Vertical Silicon Nanotube Arrays via Toroidal Micelle Self-Assembly.

We present a highly scalable, room-temperature strategy for fabricating vertical silicon nanotube arrays derived from a toroidal micelle pattern via a water vapor-induced block copolymer (BCP) self-assembly mechanism. A polystyrene-b-poly(ethylene oxide) (PS-b-PEO) BCP system can be self-assembled into toroidal micelle structures (diameter: 400–600 nm) on a PS-OH-modified substrate in a facile manner contrasting with other complex processes described in the literature. It was found that a minimum PS-b-PEO thickness of ∼86 nm is required for the toroidal self-assembly. Furthermore, a water vapor annealing treatment at room conditions (∼25 °C, 60 min) is shown to vastly enhance the ordering of micellar structures. A liquid-phase infiltration process was used to generate arrays of iron and nickel oxide nanorings. These oxide structures were used as templates for pattern transfer into the underlying silicon substrate via plasma etching, resulting in large-area 3D silicon nanotube arrays. The overall simplicity of this technique, as well as the wide potential versatility of the resulting metal structures, proves that such room-temperature synthesis routes are a viable pathway for complex nanostructure fabrication, with potential applicability in fields such as optics or catalysis.