Metamaterial Technology Research Articles

Metamaterial-Enabled Hybrid Receive Coil for Enhanced Magnetic Resonance Imaging Capabilities.

Magnetic resonance imaging (MRI) relies on high-performance receive coils to achieve optimal signal-to-noise ratio (SNR), but conventional designs are often bulky and complex. Recent advancements in metamaterial technology have led to the development of metamaterial-inspired receive coils that enhance imaging capabilities and offer design flexibility. However, these configurations typically face challenges related to reduced adaptability and increased physical footprint. This study introduces a hybrid receive coil design that integrates an array of capacitively-loaded ring resonators directly onto the same plane as the coil, preserving its 2D layout without increasing its size. Both the coil and metamaterial are individually non-resonant at the targeted Larmor frequency, but their mutual coupling induces a resonance shift, achieving a frequency match and forming a hybrid structure with enhanced SNR. Experimental validation on a 3.0 T MRI platform shows that this design allows for adjustable trade-offs between peak SNR and penetration depth, making it adaptable for various clinical imaging scenarios.

Study on the influence of geometric characteristics of micro-periodic structures with slits on sound absorption properties

In recent years, there has been considerable interest in acoustic metamaterial technology that leverages sub-wavelength scale microperiodic structures to control the behavior of sound waves for sound absorption material development. This technology offers high design flexibility in unit shapes and holds promise for the development of sound absorption materials with diverse characteristics. However, the field remains in its foundational exploration phase, with the detailed relationship between geometric shapes and sound absorption properties yet to be fully elucidated. To address this gap, we conducted a thorough investigation focusing on their relationship by examining the transport parameters of the Johnson-Champoux-Allard-Lafarge-Pride (JCALP) model, which are closely associated with sound absorption properties. We designed a cubic lattice with slits on the incident surface of the unit shape as a microperiodic structure and examined the normal incident sound absorption characteristics using the finite element method. Our results indicate that manipulation of slit partition numbers and slit widths allows for control of transport parameters, suggesting the potential to achieve various sound absorption properties.

Enhancement of broadband terahertz trace absorption spectrum based on angular multiplexing of trapezoidal dielectric grating

Terahertz spectroscopy provide a fast, label-free, and non-destructive method for detecting bio-medical molecules, with wide applications in national security, pharmacy, and healthcare. However, detecting terahertz absorption spectra of trace analytes still faces significant challenges. In recent years, metamaterial parameter multiplexing technology has been used to detect the terahertz fingerprint spectra of trace substances. This paper proposes a new structure based on the angle-multiplexing enhancement principle of a trapezoidal dielectric grating to enhance the terahertz absorption spectra of thin-film analytes. By scanning the incident wave angle, a series of resonance absorption peaks can be obtained. The enhanced absorption spectrum formed by the envelope of absorption spectrum peaks increases by 141 times compared to directly measuring the absorption spectrum of the same film. This structure provides a new and effective means for terahertz trace detection using metamaterial parameter multiplexing technology.

Ultra-broadband microwave absorber based on disordered metamaterials.

Metamaterial absorption technology plays an increasingly important role in military and civilian sectors, serving crucial functions in communication, radar technology, and electromagnetic cloaking. However, traditional metamaterial absorbers are predominantly composed of periodic structures, thus limiting their absorption bandwidth, polarization, and angular flexibility. This study employs disordered structures, utilizing their randomness and diversity, to optimize and enhance the performance of periodic structure metamaterial absorbers. Building upon a well-designed periodic perfect absorption structure, a uniform distribution function is introduced to analyze the effects of positional and size disorder on the absorptive properties of the metamaterial. The mechanisms of the disorder are further investigated through simulation analysis. Subsequently, an innovative approach based on disorder engineering for broadband enhancement of metamaterial absorbers is proposed. Numerical simulation results and experimental validations demonstrate that absorbers constructed using this method significantly broaden the absorption bandwidth while maintaining excellent angular and polarization stability. This research not only offers a new method for the design and performance optimization of metamaterial absorbers but also provides a theoretical foundation for the development of metamaterial self-assembly techniques.

The development of cloaking techniques based on phase-modulated metasurfaces

Abstract More and more attention has been paid to explore the application background of cloaking techniques based on phase-modulated metasurfaces, which play an important role in modern engineering and military applications. Phase-modulated metasurfaces are an emerging field of research that explores how the propagation of electromagnetic waves can be manipulated by precisely controlling the phase on tiny elements. These tiny elements, usually nanoscale structures, are arranged on the metasurface to precisely control the propagation and scattering of electromagnetic waves in a specific frequency range. The thesis first reviews the development of metamaterial cloaking technology, introduces the realization of several mainstream metamaterial cloaking technologies, and points out the benefits of cloaking techniques based on phase-modulated metasurfaces compared with other cloaking technologies. Then the development history of cloaking techniques based on phase-modulated metasurfaces is introduced through four key time nodes. We can find that phase-modulated metasurfaces are not only getting thinner and thinner, but in addition to the stealth effect, i.e., the reduction of the RCS (Radar Cross Section), phase-modulated metasurfaces can also simulate different virtual shapes. Finally, the development and research progress of cloaking techniques based on phase-modulated metasurfaces are summarized, and personal opinions on its future development are put forward. This paper summarizes the advances in the field of phase-modulated metasurfaces over the last decade and presents some representative approaches to phase-modulated metasurfaces at various points in time, which can help readers better understand the field of metasurfaces and metamaterials.

Identifying Factors Influencing the Properties of Vibroacoustic Metamaterials Using Three Different Acoustic Methods

Vibroacoustic metamaterials offer an approach for the targeted damping of unwanted structural vibrations and noise by integrating periodically arranged resonators into a matrix of bulk material. Fabrication using the laser bed powder fusion process allows the targeted integration of bulk resonators and powder depots, leading to an extension of the designable damping properties. Herein, the adaptation of acoustic methods is focused on the characterization of the properties of metamaterial plates. The investigated vibroacoustic metamaterial plates are made of polyamide PA1.2, combining material and structural damping. The vibration behavior of the plates over a range of frequencies using acoustic impedance measurements in a custom‐built measurement tube is investigated and it is compared with structural dynamics experiments using an electrodynamic shaker. The measurements allow for the identification of stop bands (frequency range with high damping) and influencing factors such as metamaterial design, mass, powder amountand surface on the frequency‐dependent damping properties. The adapted technique investigated in this work provides an experimental platform to characterize the complex interplay of acoustic metamaterial design and holds promise for scaling up metamaterial technology for industrial applications due to its simplicity, small space requirement, and low cost.

Bright Innovations: Review of Next-Generation Advances in Scintillator Engineering.

This review focuses on modern scintillators, the heart of ionizing radiation detection with applications in medical diagnostics, homeland security, research, and other areas. The conventional method to improve their characteristics, such as light output and timing properties, consists of improving in material composition and doping, etc., which are intrinsic to the material. On the contrary, we review recent advancements in cutting-edge approaches to shape scintillator characteristics via photonic and metamaterial engineering, which are extrinsic and introduce controlled inhomogeneity in the scintillator's surface or volume. The methods to be discussed include improved light out-coupling using photonic crystal (PhC) coating, dielectric architecture modification producing the Purcell effect, and meta-materials engineering based on energy sharing. These approaches help to break traditional bulk scintillators' limitations, e.g., to deal with poor light extraction efficiency from the material due to a typically large refractive index mismatch or improve timing performance compared to bulk materials. In the Outlook section, modern physical phenomena are discussed and suggested as the basis for the next generations of scintillation-based detectors and technology, followed by a brief discussion on cost-effective fabrication techniques that could be scalable.

Qualitative and Quantitative Detection of Typical Reproductive Hormones in Dairy Cows Based on Terahertz Spectroscopy and Metamaterial Technology.

Progesterone (PROG) and estrone (E1) are typical reproductive hormones in dairy cows. Assessing the levels of these hormones in vivo can aid in estrus identification. In the present work, the feasibility of the qualitative and quantitative detection of PROG and E1 using terahertz time-domain spectroscopy (THz-TDS) and metamaterial technology was preliminarily investigated. First, the time domain spectra, frequency domain spectra, and absorption coefficients of PROG and E1 samples were collected and analyzed. A vibration analysis was conducted using density functional theory (DFT). Subsequently, a double-ring (DR) metamaterial structure was designed and simulated using the frequency domain solution algorithm in CST Studio Suite (CST) software. This aimed to ensure that the double resonance peaks of DR were similar to the absorption peaks of PROG and E1. Finally, the response of DR to different concentrations of PROG/E1 was analyzed and quantitatively modeled. The results show that a qualitative analysis can be conducted by comparing the corresponding DR resonance peak changes in PROG and E1 samples at various concentrations. The best R2 for the PROG quantitative model was 0.9872, while for E1, it was 0.9828. This indicates that terahertz spectral-metamaterial technology for the qualitative and quantitative detection of the typical reproductive hormones PROG and E1 in dairy cows is feasible and worthy of in-depth exploration. This study provides a reference for the identification of dairy cow estrus.

Brain Stroke Detection Using Machine Learning

Abstract: We look at the skills of metamaterials technology to enhance the first-rate of reconstructed photos for the hassle of mind stroke detection. We combine the metamaterial in our headscarf system for mind imaging in CST, and evaluate the reconstructed pix of the pinnacle model this is positioned in the microwave tomographic head machine for the cases with and with out the incorporated metamaterial. For photograph reconstruction we observe the distorted Born iterative technique (DBIM) mixed with two-step iterative shrinkage/thresholding (TwIST) set of rules. Our consequences imply that using our metamaterial can increase the signal distinction due to the presence of a blood goal, which translates into more ac- curate reconstructions of the target.

Design of functionally gradient metastructure with ultra-broadband and strong absorption

Rational design principles for ultra-broadband lattice-based metastructure absorbers (MMAs) remain scarcely explored, including elucidation of the governing absorption phenomena. This work presents Octet truss lattices gradient-tailored to achieve highly efficient wide-spectrum electromagnetic (EM) wave mitigation. The optimized 15 mm thick three-dimensional printed architectures comprise three stacked sub-layers with graduated densities spanning a reflective backing. Analysis of unit cell EM responses as a function of geometric parameters facilitates concurrent broadband absorption and minimal mass. Consequently, ultra-wideband absorption below −10 dB persists from 2.84 to 40.0 GHz under normal incidence, with strongly enhanced attenuation below −15 dB between 8.51 and 40.0 GHz. Additionally, consistent absorption capacity endures up to 60° for both transverse electric (TE) and transverse magnetic (TM) polarizations, empowered by the intricate conductive networks established through wave interactions. The unique combination of additive manufacturing, hierarchical metamaterial engineering, and physical insights provides a versatile strategy for customized broadband absorption systems across application domains.

Hydrodynamic metamaterial redirector for steering fluid flow in pipelines with arbitrary curvatures

Hydrodynamic metamaterial redirector for steering fluid flow in pipelines with arbitrary curvatures

Solitons of the Twin-Core Couplers with Fractional Beta Derivative Evolution in Optical Metamaterials via Two Distinct Methods

The rapid advancements in metamaterial research have brought forth a new era of possibilities for controlling and manipulating light at the nanoscale. In particular, the design and engineering of optical metamaterials have created advances in the field of photonics, enabling the development of advanced devices with unprecedented functionalities. Among the myriad of intriguing metamaterial structures, the nonlinear directional couplers with beta derivative evolution have emerged as a significant avenue of exploration, offering remarkable potential for light propagation and manipulation. This study obtains the solitary wave solutions for twin-core couplers having spatial-temporal fractional beta derivative evolution by using two different methods, the Bernoulli method and the complete polynomial discriminant system method. By graphing some of the obtained solutions, the effect of the beta derivative has been shown. The findings would be beneficial to understand physical behaviours in nonlinear optics, particularly twin-core couplers with optical metamaterials.

Modular reverse design of acoustic metamaterial and sound barrier engineering applications: High ventilation and broadband sound insulation

A multi-gradient cavity acoustic metamaterial (MCAM) structure and a modular reverse design method (MRDM) that can realize high ventilation and broadband acoustic isolation are proposed. The method controls the deep neural network model of acoustic metamaterials through a particle swarm algorithm, and the optimized multi-gradient cavity acoustic metamaterial structure (OMCAM) can be reverse-designed by inputting only the constraints and the objective function such as the amount of noise reduction. Compared with the finite element method, the computational efficiency can be improved by about 500 times to achieve an optimized design. The acoustic simulation results show that the average noise reduction of the structure is 23.5 dB in the range of 0∼4000 Hz, and a broadband sound attenuation with 38 dB noise reduction is formed in the target frequency band of 500Hz∼2000 Hz. The acoustic experimental results of the 3D-printed structure are in agreement with the simulation results. Compared with the two existing ventilated acoustic metamaterials, the average noise reduction of OMCAM under equal ventilation capacity is improved by 10.6 dB and 17.4 dB, respectively. The sound barrier based on the proposed OMCAM design is implemented on an elevated rail transit line, showing an improvement of 9.4 dB of average noise reduction compared with existing upright railroad sound barriers. The noise reduction mechanism of the OMCAM structure was finally revealed by the sound field distribution in different modes.

Recent advances in metamaterial integrated photonics

Since the invention of the silicon subwavelength grating waveguide in 2006, subwavelength metamaterial engineering has become an essential design tool in silicon photonics. Employing well-established nanometer-scale semiconductor manufacturing techniques to create metamaterials in optical waveguides has allowed unprecedented control of the flow of light in photonic chips. This is achieved through fine-tuning of fundamental optical properties such as modal confinement, effective index, dispersion, and anisotropy, directly by lithographic imprinting of a specific subwavelength grating structure onto a nanophotonic waveguide. In parallel, low-loss mode propagation is readily obtained over a broad spectral range since the subwavelength periodicity effectively avoids losses due to spurious resonances and bandgap effects. In this review we present recent advances achieved in the surging field of metamaterial integrated photonics. After briefly introducing the fundamental concepts governing the propagation of light in periodic waveguides via Floquet–Bloch modes, we review progress in the main application areas of subwavelength nanostructures in silicon photonics, presenting the most representative devices. We specifically focus on off-chip coupling interfaces, polarization management and anisotropy engineering, spectral filtering and wavelength multiplexing, evanescent field biochemical sensing, mid-infrared photonics, and nonlinear waveguide optics and optomechanics. We also introduce a nascent research area of resonant integrated photonics leveraging Mie resonances in dielectrics for on-chip guiding of optical waves, with the first Huygens’ metawaveguide recently demonstrated. Finally, we provide a brief overview of inverse design approaches and machine-learning algorithms for on-chip optical metamaterials. In our conclusions, we summarize the key developments while highlighting the challenges and future prospects.

Investigation of SAR reduction and gain enhancement using an all-textile antenna with metamaterial structure for wireless body area network applications

This work presents a wideband, low-profile, and flexible antenna that incorporates metamaterial (MTM) structures and textile materials. The antenna design is simulated using CST Microwave Studio, incorporating flexible textile elements such as a felt substrate and conductive fabric. The developed antenna's performance was examined numerically in free space and on a human body. The antenna with MTM technology operates in the ultra-wideband (UWB) with a bandwidth ranging from 3.86 to 13 GHz. It possesses a low profile with a thickness of 5.34 mm, making it suitable for applications in wireless body area networks (WBAN). Through the integration of metamaterial structures, the antenna's gain is enhanced, reaching 8.85 dBi compared to the initial gain of 5.34 dBi. Notably, the gain consistently exceeds 6 dBi across the entire UWB range, indicating focused power in a specific direction. For applications on the human body, specific absorption rate (SAR) values were calculated and found to be well within safety limits defined by European standards. This ensures minimal back radiation when the antenna is worn on the body, enhancing signal transmission range in WBAN applications.

Brain Stroke Detection Using Machine Learning

Abstract: We look at the skills of metamaterials technology to en- hance the first-rate of reconstructed photos for the hassle of mind stroke detection. We combine the metamaterial in our headscarf system for mind imaging in CST, and evaluate the reconstructed pix of the pinnacle model this is positioned in the microwave to- mographic head machine for the cases with and with out the incorporated metamaterial.

Graphene and gold nanoparticles integrated terahertz metasurface for improved sensor sensitivity

Terahertz metamaterial technology, as an efficient nondestructive testing method, has shown great development potential in the detection of biological samples. In this study, we have proposed a graphene-integrated gold nanoparticles (AuNPs) terahertz (THz) biosensor and have analyzed the sensing performance of four IC-type resonators (ICSRs) for biosensors: bare ICSRs, ICSRs-integrated AuNPs, ICSRs-integrated graphene, and ICSRs-integrated graphene and AuNPs. The AuNPs generate charge accumulation and induce local electric field enhancement due to the tip effect, and enhance the interaction between the THz wave and the analyte, thus improving the sensitivity of the sensor. The combination of AuNPs and ICSRs-integrated graphene results in sensors with more pronounced amplitude changes and higher sensitivity. Due to the Fermi energy level of graphene being close to the Dirac point, the sensor is ultra-sensitive to external stimuli with a limit of detection of 10.48 fg/ml for aspartic acid solutions. This biosensor has the potential to detect trace amino acids with high sensitivity, contributing to early disease detection and environmental detection for early diagnosis and ecological balance.

A Compact Metamaterial Dual-band Branch-line Coupler for 5G Applications

This study introduces a compact branch-line coupler (BLC) based on metamaterial (MTM) technology that can operate in sub-6 GHz 5G frequency bands. Conventional vertical and horizontal sections of the BLC were replaced with T-shaped TLs and interdigital capacitor (IDC) unit cells incorporated into the BLC sections to improve their performance and reduce their dimensions. The BLC is designed on a Rogers RT5880 substrate material, and it operates at dual frequencies of 0.7 GHz and 3.5 GHz. The design was simulated using CST Microwave Studio software and achieved enhanced frequency band ratio.

Review and perspective on acoustic metamaterials: From fundamentals to applications

In the past two decades, the research on acoustic metamaterials has flourished, which is also benefited from the development of additive manufacturing technology. The exotic physical phenomena and principles exhibited by acoustic metamaterials have attracted widespread attention from academia and engineering communities, which can be applied to noise reduction and acoustic nondestructive testing in industrial; invisible cloaking and camouflage in the military; medical ultrasound imaging in national health; acoustic stealth in defense security, detection in the ocean, communication, and other fields, i.e., acoustic metamaterials have important scientific research value and broad application prospects. This review summarizes the history and research status of acoustic metamaterials, focusing on the main research progress of metamaterials in nonlinear acoustic and acoustic coatings fields, including the research on acoustic coatings with cavities of our group. Finally, the future development direction of acoustic metamaterials is prospected, and the difficulties and challenges faced by the actual engineering of acoustic metamaterials are discussed, such as difficulties in mass production, hydrostatic pressure resistant property, omnidirectional wave control, high production costs, and so on.

Deep Transfer Learning-Based Multi-Modal Digital Twins for Enhancement and Diagnostic Analysis of Brain MRI Image.

it aims to adopt deep transfer learning combined with Digital Twins (DTs) in Magnetic Resonance Imaging (MRI) medical image enhancement. MRI image enhancement method based on metamaterial composite technology is proposed by analyzing the application status of DTs in medical direction and the principle of MRI imaging. On the basis of deep transfer learning, MRI super-resolution deep neural network structure is established. To address the problem that different medical imaging methods have advantages and disadvantages, a multi-mode medical image fusion algorithm based on adaptive decomposition is proposed and verified by experiments. the optimal Peak Signal to Noise Ratio (PSNR) of 34.11dB can be obtained by introducing modified linear element and loss function of deep transfer learning neural network structure. The Structural Similarity Coefficient (SSIM) is 85.24%. It indicates that the MRI truthfulness and sharpness obtained by adding composite metasurface are improved greatly. The proposed medical image fusion algorithm has the highest overall score in the subjective evaluation of the six groups of fusion image results. Group III had the highest score in Magnetic Resonance Imaging- Positron Emission Computed Tomography (MRI-PET) image fusion, with a score of 4.67, close to the full score of 5. As for the objective evaluation in group I of Magnetic Resonance Imaging- Single Photon Emission Computed Tomography (MRI-SPECT) images, the Root Mean Square Error (RMSE), Relative Average Spectral Error (RASE) and Spectral Angle Mapper (SAM) are the highest, which are 39.2075, 116.688, and 0.594, respectively. Mutual Information (MI) is 5.8822. the proposed algorithm has better performance than other algorithms in preserving spatial details of MRI images and color information direction of SPECT images, and the other five groups have achieved similar results.