Applications Of Metamaterials Research Articles

Multilayer coupled plate-type acoustic metamaterials for low-frequency broadband sound insulation

Acoustic metamaterials have been becoming a popular topic for the better sound insulation at low frequency than traditional materials. However, due to the local resonance mechanism, this excellent performance can only be demonstrated in narrow frequency bands. Therefore, multilayer coupled plate-type acoustic metamaterials (MPAM) are proposed in this paper. The structure consists of a large plate-type acoustic metamaterial (PAM) with periodic square metamaterial units and double-layer fibers with different densities. According to finite element study on the insertion loss (IL) of the MPAM, the governing physical mechanism of the MPAM was analyzed according to the sound pressure level distributions and the vibration modes of the PAM layer. In addition, large-scale MPAM samples with a size of 506 mm*506 mm were manufactured, the reverberation and anechoic chamber was employed to verify the sound insulation performance. It can be concluded from the test results that the IL peak originate from the anti-resonance of the PAM layer rather than the weight of the materials. Compared to the structures without PAM layer, in the range of 360 Hz−950 Hz, the IL is increased by 5 dB at least and up to 17 dB at most. The influences of the incident angles, the frame density and the coverage rate of the PAM layer on the IL are disscussed. The proposed MPAM structure, analytical techniques and test results may be helpful for the engineering application of acoustic metamaterials.

First-principles study of the optical properties of BaMoO[formula omitted]/SrHfO[formula omitted] hyperbolic metamaterials

The theoretical applications of hyperbolic metamaterials have generated excitement in multiple fields, particularly in super-resolution optics. In practice, however, the potential of HMMs has been limited by the shortcomings of their constituent parts. Primarily, these are high losses and instabilities in the metal component, which is typically gold or silver, and excessive thickness in both types of layers. In this paper, we use density functional theory to investigate BaMoO3-SrHfO3 metamaterials. We predict that these are hyperbolic throughout the visible range and have the potential to mitigate many of these limitations, including a significant loss reduction. We also examine the accuracy of the effective-medium theory, which is used to predict the bulk optical properties of multilayered HMMs.

Metamaterials for Acoustic Noise Filtering and Energy Harvesting.

Artificial methods for noise filtering are required for the twenty-first century's Factory vision 4.0. From various perspectives of physics, noise filtering capabilities could be addressed in multiple ways. In this article, the physics of noise control is first dissected into active and passive control mechanisms and then further different physics are categorized to visualize their respective physics, mechanism, and target of their respective applications. Beyond traditional passive approaches, the comparatively modern concept for sound isolation and acoustic noise filtering is based on artificial metamaterials. These new materials demonstrate unique interaction with acoustic wave propagation exploiting different physics, which is emphasized in this article. A few multi-functional metamaterials were reported to harvest energy while filtering the ambient noise simultaneously. It was found to be extremely useful for next-generation noise applications where simultaneously, green energy could be generated from the energy which is otherwise lost. In this article, both these concepts are brought under one umbrella to evaluate the applicability of the respective methods. An attempt has been made to create groundbreaking transformative and collaborative possibilities. Controlling of acoustic sources and active damping mechanisms are reported under an active mechanism. Whereas Helmholtz resonator, sound absorbing, spring-mass damping, and vibration absorbing approaches together with metamaterial approaches are reported under a passive mechanism. The possible application of metamaterials with ventilation while performing noise filtering is reported to be implemented for future Smart Cities.

Enhancement of sound absorption performance of Helmholtz resonators by space division and chamber grouping

Sound absorption performance of the Helmholtz resonator was enhanced by space division and chamber grouping in this research, which aimed to achieve high sound absorption coefficient and broad absorption band simultaneously. Based on acoustic finite element simulation, it could be found that the effective sound absorption frequency band of multiple divided Helmholtz resonators shifted to high frequency direction and the effective absorption bandwidth rose gradually with the increase of division number Ns from 1 to 24, and the effective sound absorption band of multiple divided and grouped Helmholtz resonators with the certain division number Ns would shift to the high frequency direction gradually and its width was improved normally with the increase of grouping number Gs. Moreover, the multiple divided and grouped Helmholtz resonators with division number Ns = 18 and grouping number Gs = 6 was optimized for the certain practical demand, and the optimal geometric parameters were obtained by the joint simulation method incorporating the finite element simulation and the cuckoo search algorithm. Furthermore, its actual sound absorption coefficients were obtained through sample fabrication by the additive manufacturing and standing wave tube measurement by the AWA6290T, and all the actual sound absorption coefficients in 400–800 Hz were above 0.8 and the average value in this range was up to 0.8729 with limited total thickness of 40 mm. Enhancement of the sound absorption performance of multiple divided and grouped Helmholtz resonators would be favorable to promote the practical applications of acoustic metamaterials in the noise reduction field.

Sandwich meta-panels for vibration and explosion attenuation: Manufacturing, testing, and analyzing

In this research, composite sandwich meta-panels were designed, made and tested. The vibration and explosion attenuation effects of the meta-panel were revealed by frequency sweep tests, in-field explosion experiments, and finite element modeling (FEM). Meta-panel theory was also applied to predict the dynamic behavior. The local resonance metamaterial panel shows extraordinary vibration attenuation and explosion mitigation effects. The bandwidth of the meta-panel can reach 300 Hz, and the peak displacement can be reduced to 70% or less of that of the ordinary sandwich panel. The peak strain of the facesheet is reduced as well. The research provides an experimental basis for the application of metamaterials in protective buildings.

Application of vibroacoustic metamaterials for structural vibration reduction in space structures

This contribution presents research activities on vibroacoustic metamaterials (VAMM) based on the resonance effect for application in space structures to reduce structural vibrations. The focus of this work is the development of a design process for conception, numerical simulation, and manufacturing of vibroacoustic metamaterials as well as an experimental demonstration of the vibration reduction effect. The technology of VAMM is applied to representative scaled down launcher and satellite components. The vibration reduction behavior is tailored to each component, dependant on requirements on additional mass, manufacturing considerations and frequency range. A high potential is shown for all demonstrators, giving a bright outlook for further development and implementation of VAMM components for launcher and space components.

Noise Control in Air Mechanical Ventilation Systems with Three-Dimensional Metamaterials

The diffusion of mechanical ventilation systems increased rapidly due to the climate changes in all parts of the world. The mechanical ventilation systems are mainly used in the summer for many difficulties to face very hot temperatures. One of the biggest problems considered if every residential unit is equipped with a mechanical ventilation system is the generation of noise by the rotating blades of the fan for refrigeration. This paper discusses the applications of metamaterials to create attenuation filters to be installed inside the encases of the mechanical ventilation systems in order to obtain sound attenuation. A three-dimensional reticular structure made with spheres has been studied in different configurations related to the numbers of layers employed. The sound attenuations were measured at some specific octaves, depending on the particular configurations. In general, the sound attenuation peaks have been measured between 4 kHz and 8 kHz; this is expected to mitigate the tonal noise component typical of fans based on different variables that compose the whole system (e.g., fan diameter, number of blades, fan speed). However, the outcomes shall be considered in terms of laboratory conditions since material properties of the enclosure and potential polarization effects due to reflection of sound waves at the boundaries may occur.

Evanescent waves in hybrid poroelastic metamaterials with interface effects

The propagation of evanescent waves in hybrid poroelastic metamaterials is investigated by considering interface effects. Hybrid metamaterials consist of a single-phased (acoustic or elastic) medium and a poroelastic medium. To establish the finite element model of elastic/poroelastic and fluid/poroelastic interfaces, weak integral forms of wave equations for elastic, fluid, and poroelastic media and boundary conditions at the interfaces between different media are first given. Next, the expressions for displacement and pressure in the frame of Bloch’s theorem are substituted into the dynamical equations to obtain general forms suitable for periodic metamaterials, from which the complex band structure and the frequency response of hybrid metamaterials are calculated. The influence of geometrical and material parameters, as well as the viscosity of the pore fluid on the propagation of elastic waves are discussed. The results and discussions show that flat bands and narrow locally resonant band gaps appear for elastic/poroelastic metamaterials. A quasi-resonance Bragg band gap is formed in the case of an elastic inclusion in a poroelastic matrix. Furthermore, a transition from an avoided crossing to a wave-number band gap is obtained by adjusting the geometrical and material parameters of the elastic inclusion. For the case of fluid inclusion in a poroelastic matrix with the open-pore interface, a cut-off frequency for the fast longitudinal wave is observed. However, only an avoided crossing is produced for the sealed-pore interface. For both cases, the phase velocity of the shear vertical (SV) wave decreases faster than that of the slow longitudinal wave as the radius of the inclusion increases. When the viscosity of the pore fluid is considered for elastic inclusion in a poroelastic matrix, the transmission dip at the ‘quasi-resonance Bragg’ band gap disappears. However, the transmission dip in the locally resonant band gap of the SV wave becomes slightly shallower and smoother than in the inviscid case. This study is relevant to practical applications of hybrid single-phased and poroelastic metamaterials, e.g., for coastal engineering and civil engineering.

Design and Fabrication of a Low-Cost, Multiband and High Gain Square Tooth-Enabled Metamaterial Superstrate Microstrip Patch Antenna.

The manuscript represents a novel square tooth-enabled superstrate metamaterial loaded microstrip patch antenna for the multiple frequency band operation. The proposed tooth-based metamaterial antenna provides better gain and directivity. Four antenna structures are numerically investigated for the different geometry of the patch and tooth. These proposed structures are simulated, fabricated, measured, and compared for the frequency range of 3 GHz to 9 GHz. The electrical equivalent model of the split-ring resonator is also analyzed in the manuscript. The comparative analysis of all of the proposed structures has been carried out, in terms of several bands, reflectance response, VSWR, gain and bandwidth. The results are compared with previously published works. The effects are simulated using a high-frequency structure simulator tool with the finite element method. The measured and fabricated results are compared for verification purposes. The proposed structure provides seven bands of operation and 8.57 dB of gain. It is observed that the proposed design offers the multiple frequency band operation with a good gain. The proposed tooth-based metamaterial antenna suits applications, such as the surveillance radar, satellite communication, weather monitoring and many other wireless devices.

Origami Tribo-Metamaterials with Mechanoelectrical Multistability

The emerging mechanical functional metamaterials reported with promising mechanoelectrical characteristics bring increasing attention to structurally functional materials. It is essential to deploy mechanical metamaterials in energy materials for effective triggering and controllable mechanoelectrical response. This study reports origami tribo-metamaterials (OTMs) that design triboelectric materials in the origami-enabled, tubular metamaterials. The octagonal, hexagonal, and conical origami units are deployed as the metamaterial substrates to trigger the triboelectric pairs for mechanoelectrical multistability. For the octagonal OTM configuration with the triboelectric pair of fluorinated ethylene propylene-paper, the peak open-circuit voltage, short-circuit current, and transferred charge are obtained as 206.4 V, 4.66 μA, and 0.38 μC, respectively, and the maximum instantaneous output power density is 0.96 μW/cm2 with the load resistance of 20 MΩ. The OTM takes advantage of the origami metamaterials to obtain the multistable force-displacement response as effective stimuli for the triboelectric materials, which leads to tunable mechanoelectrical performance for speed and weight sensing and energy harvesting. The proposed OTM not only offers a strategy to structurally design energy materials to achieve desirable mechanoelectrical response, but also provides a guideline for the applications of mechanical functional metamaterials in practice.

Prospects on application of elastic metamaterials in acoustic emission sensing

This paper discusses challenges, limitations and problems arising in currently employed acoustic emission testing systems, sensors and signal processing algorithms. Main factors influencing and compromising accuracy and reliability of the classically used methods are briefly analyzed. Next, metamaterials and their dynamic properties are outlined with the aim and focus on their potential in manipulating energy flow. Several applications of metamaterials in acoustic emission are presented that indicate their potential in acoustic emission. Finally, possibilities of designing a new type of sensor for acoustic emission using metamaterials is discussed. As a consequence, it is expected to increase sensitivity and accuracy of source localization with smaller number of sensors used during measurements.

Applications of negative permeability metamaterials for electromagnetic resonance type wireless power transfer systems

With the development of electric drive systems such as unmanned aerial vehicles and electric vehicles, the charging problem of power supply devices has become increasingly prominent. However, the traditional charging method requires physical circuits, which makes it impossible to achieve freedom of the position in actual use. The wireless power transmission technology, which mainly relies on electromagnetic wave to complete energy transmission, is expected to get rid of the restriction of physical space location and solve the problem of charging location, which has great potential in medical treatment, rescue, detection and other fields. However, the low transmission efficiency and short transmission distance caused by electromagnetic field leakage are the two main problems faced by radio energy transmission systems. In general, with the increase of transmission distance, the transmission efficiency will drop sharply. Fortunately, inserting a negative permeability metamaterial with extraordinary electromagnetic characteristics into the transmitting and receiving coils will greatly alleviate this attenuation trend and can also shield electromagnetic radiation to a certain extent. In this paper, some experiments of negative permeability metamaterials used in electromagnetic resonance type wireless power transfer systems are summarized for reference.

3D Chiral Metamaterials for Biosensing - INVITED

In this contribution we will discuss the experimental application of 3D chiral metamaterials as high sensitivity biosensors, exploiting circular dichroism in transmission. 3D metamaterials with chiral features can be realized by highly accurate and highly localized bottom-up nanofabrication approach. Large chiroptical effects can be engineered, originating from the single element optical resonances, but collective interactions in arrayed configurations can play a significant role, further enhancing these effects. Capability of biomarker detection in the femtomolar range is demonstrated even in complex biofluid matrix.

Evaluation of waste in seismic metamaterial applications

Within the scope of this study, a simulation study was carried out in order to prove the usability of waste in seismic metamaterial studies. In the study, a square array field application was preferred, and a 3-layer cylindrical pile design was used. In addition, direct contact of waste with soil and direct air is prevented. Within the scope of the study, polypropylene, which is frequently contained in medical products, concrete as a containment layer, and lime materials to prevent leakage of hazardous waste were used as materials. In addition, a design has been made within the soil structure as the ground structure. As a result of the study, it was determined that transmission losses occur in low frequency regions such as 3-10 Hz values due to obtaining partial band gaps. In addition, when looking at the propagation of the vibration waves in the field plane depending on the time, it is seen that the waves are significantly reduced, and the results are promising.

Broadband Labyrinthine Acoustic Insulator

Ventilated acoustic insulation currently represents one of the most promising research directions in applied acoustics. With the ongoing development and application of acoustic metamaterials, tremendous progress has been made in this space. In this work, we propose a ventilated acoustic insulator based on a labyrinthine metamaterial, a design that consists of a peripheral, circumferential labyrinthine region and a central ventilated, open region. Herein, we demonstrate the potential for this design to yield high-performance wide-band acoustic insulation, a performance metric currently lacking in this class of acoustic silencers, in combination with ventilation. The silencing effect of the labyrinthine acoustic insulator is theoretically and experimentally verified in the frequency range from 1025 to 2000 Hz. Our reported design establishes the foundation for the development of increasingly broadband ventilated acoustic insulators.

A review of underwater acoustic metamaterials for underwater acoustic equipment

Researchers use underwater acoustic equipment to explore the unknown ocean environment, which is one of the important means to understand and utilize the ocean. For underwater acoustic equipment, the application of underwater acoustic metamaterials is the premise to ensure and improve the performance of underwater acoustic communication, acoustic stealth, and sonar detection. Due to the limitations of mass density law and high hydrostatic pressure, traditional underwater acoustic materials cannot effectively absorb low-frequency sound waves and have low efficiency of elastic energy conversion. The sound absorption effect is poor under low frequency and high hydrostatic pressure. In recent years, with the development of acoustic metamaterials technology, all kinds of underwater acoustic metamaterials have also been proposed. Compared with sound waves propagating in the air, underwater sound is more difficult to control than air sound with the same frequency, so the design of underwater acoustic metamaterials is more complicated. This paper reviews the basic characteristics, development history of sound absorption, sound insulation decoupling, and underwater acoustic guided metamaterials, then the existing problems and the future development direction of underwater acoustic metamaterials are discussed.

Deep‐Subwavelength Optical Spin Textures in Volume Plasmon Polaritons with Hyperbolic Metamaterials

AbstractHyperbolic metamaterials can support extremely high‐k wavevectors, also known as volume plasmon polaritons, with highly directional propagation and light confinement to deep‐subwavelength scales. The number of high‐k modes has an inverse relationship with the overall thickness of hyperbolic metamaterials. Here, the optical spin textures from high‐k mode polaritons on the surface of silica–silver multilayer hyperbolic metamaterials are studied. The results demonstrate that with an increase in the overall thickness, the spin texture changes from a twisted structure to a Néel‐type photonic skyrmion, due to the decrease in the number of high‐k modes. Moreover, the size of a single photonic skyrmion is less than 1/2 of the light wavelength, and the full width at half maximum of the spin angular momentum is less than 1/9 of the light wavelength. This work is expected to facilitate new applications of hyperbolic metamaterials, such as spin‐dependent excitation and detection devices at the deep‐subwavelength level.

First-principle study on electronic structures and optical properties of Au-Cu intermetallic compounds

The optical properties of Au-Cu intermetallic compounds can be tailored by varying the components, which advances their promising applications in plasmonics and optical metamaterials. However, physical insight on how components tailor the electronic structures and optical properties of those Au-Cu intermetallic compounds still lacks. In this work, first-principle study on the electronic structures and optical properties of three intermetallic compounds Au 3 Cu, AuCu and AuCu 3 is presented. The influence of components on the electronic structure, electron-phonon coupling, dielectric function and electrical resistivity are fully investigated. The calculation of dielectric function is divided into interband and intraband part. The calculated interband dielectric function show large differences compared with that of pure Au and pure Cu, with an absorption peak emerging at low energy of around 0.3 eV. The temperature effect of intraband dielectric function is investigated by considering electron-phonon interaction. By superimposing the interband and intraband contribution, the total dielectric function of AuCu 3 and AuCu shows an overall good agreement with available experimental data in literature. The calculated electron-phonon coupling strength of Au 3 Cu is higher than that of pure Au and Cu, whereas, the results of AuCu and AuCu 3 are lower than them. In addition, the calculated electrical resistivity of all the three Au-Cu compounds are larger than that of pure Au and Cu. • The changes of electronic structure, electron-phonon coupling strength, and optical properties for different components are presented. • The electron-phonon coupling strength of AuCu and AuCu 3 is lower than that of pure Au and Cu. • The electrical resistivity of Au-Cu compound is higher than pure Au and Cu.

Dual-Function Metasurface for Tunable Selective Absorption.

Metamaterials have become a powerful technique in interdisciplinary research, especially in the field of designing terahertz devices. In this paper, two pairs of different structural units of aluminum-polymer composite metamaterials (APCM) for tunable selectivity are designed. One is designed to achieve high-contrast near-field imaging of linear polarized waves, the other is designed to achieve high-contrast near-field imaging of circularly polarized waves, which means the structural units have very large circular dichroisms. After theoretical design and simulation optimization, it can be found that the contrast of near-field imaging can be effectively controlled by using vanadium oxide (VO2) to fill the open gap of the structure. When the conductivity of VO2 is 200 S/m, both the reflection difference under linear polarization excitation and the reflection difference under the excitation of the circularly polarized wave are at the maximum. The former has a modulation depth of 0.8, and the latter has a modulation depth of 0.55. This work shows excellent tunable selective absorption ability, which will promote the application of metamaterials in terahertz absorber, such as biomedical, non-destructive testing, security inspection, wireless communication and so on.

A review of piezoelectric metamaterials for underwater equipment

As an important tool for monitoring the marine environment, safeguarding maritime rights and interests and building a smart ocean, underwater equipment has developed rapidly in recent years. Due to the problems of seawater corrosion, excessive deep-sea static pressure and noise interference in the marine environment and economy, the applicability of manufacturing materials must be considered at the beginning of the design of underwater equipment. Piezoelectric metamaterial is widely used in underwater equipment instead of traditional materials because the traditional materials can not meet the application requirements. In this paper, according to the application range of piezoelectric metamaterials in underwater equipment, the current application of piezoelectric metamaterials is reviewed from the aspects of sound insulation and energy conversion. On this basis, the future development prospect of piezoelectric metamaterials in underwater equipment is introduced.