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1
Hamid, Sofian. "Design of Multiband Miniaturized Antenna using Metamaterial Concept for WLAN/WiMAX Application". JURNAL Al-AZHAR INDONESIA SERI SAINS DAN TEKNOLOGI 1, n. 1 (4 marzo 2011): 1. http://dx.doi.org/10.36722/sst.v1i1.11.
Testo completoAbstract (sommario):
Design of low cost multiband antenna is presented. The antenna works in WLAN/WMAX band and has a very compact dimension of 2 cm x 2 cm, making it suitable for handheld devices. This small dimension is achieved since the antenna is loaded with the metamateria element. To miniaturize the antenna dimension further, modification on the left side of ground-plane is introduced, which is inspired by the self complementary antenna concept. Resonance at lower frequency is given by the single cell metamaterial loading on 2.36 – 2.45 frequency; at the middle frequency is given by the thin slot on 3.26 – 3.49 frequency; and at higher frequency is given by the main radiator on 5.3 – 6 GHz frequency. The antenna has omnidirectional pattern and moderate directivity of 2-3 dBi on those frequencies.
2
Nasiri, Badr, Ahmed Errkik, Jamal Zbitou, Abdelali Tajmouati, Larbi El Abdellaoui e Mohamed Latrach. "A Compact Planar Low-Pass Filter Based on SRR-Metamateria". International Journal of Electrical and Computer Engineering (IJECE) 8, n. 6 (1 dicembre 2018): 4972. http://dx.doi.org/10.11591/ijece.v8i6.pp4972-4980.
Testo completoAbstract (sommario):
In this work, a novel design of a Microstrip Low-pass filter based on metamaterial square split ring resonators (SRRs) is proposed. The SRRs has been added to obtain a reduced size and high performances. The filter is designed on an FR-4 substrate having a thickness of 1.6mm, a dielectric constant of 4.4 and loss tangent of 0.025. The proposed low-pass filter is characterized by a cutoff frequency of 2.4 GHz and an attenuation level below than -20dB in the stopband. The LPF is designed, simulated and optimized by using two electromagnetic solvers CST microwave studio and ADS. The computed results obtained by both solvers are in good agreement. The total surface area of the proposed circuit is 18x18mm2 excluding the feed line, its size is miniaturized by 40% compared to the conventional filter. The experimental results illustrate that the filter achieves very good electrical performances in the passband with a low insertion loss of 0.2 dB. Moreover, a suppression level can reach more than 35 dB in the rejected band.
3
Tan, Plum e Singh. "Surface Lattice Resonances in THz Metamaterials". Photonics 6, n. 3 (26 giugno 2019): 75. http://dx.doi.org/10.3390/photonics6030075.
Testo completoAbstract (sommario):
Diffraction of light in periodic structures is observed in a variety of systems including atoms, solid state crystals, plasmonic structures, metamaterials, and photonic crystals. In metamaterials, lattice diffraction appears across microwave to optical frequencies due to collective Rayleigh scattering of periodically arranged structures. Light waves diffracted by these periodic structures can be trapped along the metamaterial surface resulting in the excitation of surface lattice resonances, which are mediated by the structural eigenmodes of the metamaterial cavity. This has brought about fascinating opportunities such as lattice-induced transparency, strong nearfield confinement, and resonant field enhancement and line-narrowing of metamaterial structural resonances through lowering of radiative losses. In this review, we describe the mechanisms and implications of metamaterial-engineered surface lattice resonances and lattice-enhanced field confinement in terahertz metamaterials. These universal properties of surface lattice resonances in metamaterials have significant implications for the design of resonant metamaterials, including ultrasensitive sensors, lasers, and slow-light devices across the electromagnetic spectrum.
4
Ren, Yi, Minghui Duan, Rui Guo e Jing Liu. "Printed Transformable Liquid-Metal Metamaterials and Their Application in Biomedical Sensing". Sensors 21, n. 19 (22 settembre 2021): 6329. http://dx.doi.org/10.3390/s21196329.
Testo completoAbstract (sommario):
Metamaterial is becoming increasingly important owing to its unique physical properties and breakthrough applications. So far, most metamaterials that have been developed are made of rigid materials and structures, which may restrict their practical adaptation performances. Recently, with the further development of liquid metal, some efforts have explored metamaterials based on such tunable electronic inks. Liquid metal has high flexibility and good electrical conductivity, which provides more possibilities for transformable metamaterials. Here, we developed a new flexible liquid-metal metamaterial that is highly reconfigurable and could significantly extend the working limit facing current devices. The printed electronics method was adopted to fabricate artificial units and then construct various potential transformable metamaterials. Based on metamaterial theory and printing technology, typical structured flexible liquid-metal electromagnetic metamaterials were designed and fabricated. The electronic and magnetic characteristics of the liquid-metal-based electromagnetic metamaterials were evaluated through simulated analysis and experimental measurement. Particularly, the potential of liquid-metal metamaterials in biomedical sensing was investigated. Further, the future outlook of liquid-metal metamaterials and their application in diverse categories were prospected.
5
Zhou, Xiaoshu, Qide Xiao e Han Wang. "Metamaterials Design Method based on Deep learning Database". Journal of Physics: Conference Series 2185, n. 1 (1 gennaio 2022): 012023. http://dx.doi.org/10.1088/1742-6596/2185/1/012023.
Testo completoAbstract (sommario):
Abstract In recent years, deep learning has risen to the forefront of many fields, overcoming challenges previously considered difficult to solve by traditional methods. In the field of metamaterials, there are significant challenges in the design and optimization of metamaterials, including the need for a large number of labeled data sets and one-to-many mapping when solving inverse problems. Here, we will use deep learning methods to build a metamaterial database to achieve rapid design and analysis methods of metamaterials. These technologies have significantly improved the feasibility of more complex metamaterial designs and provided new metamaterial design and analysis ideas.
6
Li, Yafei, Jiangtao Lv, Qiongchan Gu, Sheng Hu, Zhigang Li, Xiaoxiao Jiang, Yu Ying e Guangyuan Si. "Metadevices with Potential Practical Applications". Molecules 24, n. 14 (22 luglio 2019): 2651. http://dx.doi.org/10.3390/molecules24142651.
Testo completoAbstract (sommario):
Metamaterials are “new materials” with different superior physical properties, which have generated great interest and become popular in scientific research. Various designs and functional devices using metamaterials have formed a new academic world. The application concept of metamaterial is based on designing diverse physical structures that can break through the limitations of traditional optical materials and composites to achieve extraordinary material functions. Therefore, metadevices have been widely studied by the academic community recently. Using the properties of metamaterials, many functional metadevices have been well investigated and further optimized. In this article, different metamaterial structures with varying functions are reviewed, and their working mechanisms and applications are summarized, which are near-field energy transfer devices, metamaterial mirrors, metamaterial biosensors, and quantum-cascade detectors. The development of metamaterials indicates that new materials will become an important breakthrough point and building blocks for new research domains, and therefore they will trigger more practical and wide applications in the future.
7
Hu, Hua-Liang, Ji-Wei Peng e Chun-Ying Lee. "Dynamic Simulation of a Metamaterial Beam Consisting of Tunable Shape Memory Material Absorbers". Vibration 1, n. 1 (18 luglio 2018): 81–92. http://dx.doi.org/10.3390/vibration1010007.
Testo completoAbstract (sommario):
Metamaterials are materials with an artificially tailored internal structure and unusual physical and mechanical properties such as a negative refraction coefficient, negative mass inertia, and negative modulus of elasticity, etc. Due to their unique characteristics, metamaterials possess great potential in engineering applications. This study aims to develop new acoustic metamaterials for applications in semi-active vibration isolation. For the proposed state-of-the-art structural configurations in metamaterials, the geometry and mass distribution of the crafted internal structure is employed to induce the local resonance inside the material. Therefore, a stopband in the dispersion curve can be created because of the energy gap. For conventional metamaterials, the stopband is fixed and unable to be adjusted in real-time once the design is completed. Although the metamaterial with distributed resonance characteristics has been proposed in the literature to extend its working stopband, the efficacy is usually compromised. In order to increase its adaptability to time-varying disturbance, several semi-active metamaterials have been proposed. In this study, the incorporation of a tunable shape memory alloy (SMA) into the configuration of metamaterial is proposed. The repeated resonance unit consisting of SMA beams is designed and its theoretical formulation for determining the dynamic characteristics is established. For more general application, the finite element model of this smart metamaterial is also derived and simulated. The stopband of this metamaterial beam with different configurations in the arrangement of the SMA absorbers was investigated. The result shows that the proposed model is able to predict the unique dynamic characteristics of this smart metamaterial beam. Moreover, the tunable stopband of the metamaterial beam with controlling the state of SMA absorbers was also demonstrated.
8
Gu, Leilei, Hongzhan Liu, Zhongchao Wei, Ruihuan Wu e Jianping Guo. "Optimized Design of Plasma Metamaterial Absorber Based on Machine Learning". Photonics 10, n. 8 (27 luglio 2023): 874. http://dx.doi.org/10.3390/photonics10080874.
Testo completoAbstract (sommario):
Metamaterial absorbers have become a popular research direction due to their broad application prospects, such as in radar, infrared imaging, and solar cell fields. Usually, nanostructured metamaterials are associated with a large number of geometric parameters, and traditional simulation designs are time consuming. In this paper, we propose a framework for designing plasma metamaterial absorbers in both a forward prediction and inverse design composed of a primary prediction network (PPN) and an auxiliary prediction network (APN). The framework can build the relationship between the geometric parameters of metamaterials and their optical response (reflection spectra, absorption spectra) from a large number of training samples, thus solving the problem of time-consuming and case-by-case numerical simulations in traditional metamaterial design. This framework can not only improve forward prediction more accurately and efficiently but also inverse design metamaterial absorbers from a given required optical response. It was verified that it is also applicable to absorbers of different structures and materials. Our results show that it can be used in metamaterial absorbers, chiral metamaterials, metamaterial filters, and other fields.
9
Kaschke, Johannes, e Martin Wegener. "Optical and Infrared Helical Metamaterials". Nanophotonics 5, n. 4 (1 settembre 2016): 510–23. http://dx.doi.org/10.1515/nanoph-2016-0005.
Testo completoAbstract (sommario):
AbstractBy tailoring metamaterials with chiral unit cells, giant optical activity and strong circular dichroism have been achieved successfully over the past decade. Metamaterials based on arrays of metal helices have revolutionized the field of chiral metamaterials, because of their capability of exhibiting these pronounced chiro-optical effects over previously unmatched bandwidths. More recently, a large number of new metamaterial designs based on metal helices have been introduced with either optimized optical performance or other chiro-optical properties for novel applications.The fabrication of helical metamaterials is, however, challenging and even more so with growing complexity of the metamaterial designs. As conventional two-dimensional nanofabrication methods, for example, electron-beam lithography, are not well suited for helical metamaterials, the development of novel three-dimensional fabrication approaches has been triggered.Here, we will discuss the theory for helical metamaterials and the principle of operation. We also review advancements in helical metamaterial design and their limitations and influence on optical performance. Furthermore, we will compare novel nano- and microfabrication techniques that have successfully yielded metallic helical metamaterials. Finally, we also discuss recently presented applications of helical metamaterials extending beyond the use of far-field circular polarizers.
10
Hou, Zheyu, Pengyu Zhang, Mengfan Ge, Jie Li, Tingting Tang, Jian Shen e Chaoyang Li. "Metamaterial Reverse Multiple Prediction Method Based on Deep Learning". Nanomaterials 11, n. 10 (11 ottobre 2021): 2672. http://dx.doi.org/10.3390/nano11102672.
Testo completoAbstract (sommario):
Metamaterials and their related research have had a profound impact on many fields, including optics, but designing metamaterial structures on demand is still a challenging task. In recent years, deep learning has been widely used to guide the design of metamaterials, and has achieved outstanding performance. In this work, a metamaterial structure reverse multiple prediction method based on semisupervised learning was proposed, named the partially Conditional Generative Adversarial Network (pCGAN). It could reversely predict multiple sets of metamaterial structures that can meet the needs by inputting the required target spectrum. This model could reach a mean average error (MAE) of 0.03 and showed good generality. Compared with the previous metamaterial design methods, this method could realize reverse design and multiple design at the same time, which opens up a new method for the design of new metamaterials.
11
Sun, Zhanshuo, Xin Wang, Junlin Wang, Hao Li, Yuhang Lu e Yu Zhang. "Switchable Multifunctional Terahertz Metamaterials Based on the Phase-Transition Properties of Vanadium Dioxide". Micromachines 13, n. 7 (27 giugno 2022): 1013. http://dx.doi.org/10.3390/mi13071013.
Testo completoAbstract (sommario):
Currently, terahertz metamaterials are studied in many fields, but it is a major challenge for a metamaterial structure to perform multiple functions. This paper proposes and studies a switchable multifunctional multilayer terahertz metamaterial. Using the phase-transition properties of vanadium dioxide (VO2), metamaterials can be controlled to switch transmission and reflection. Transmissive metamaterials can produce an electromagnetically induced transparency-like (EIT-like) effect that can be turned on or off according to different polarization angles. The reflective metamaterial is divided into I-side and II-side by the middle continuous VO2 layer. The I-side metamaterials can realize linear-to-circular polarization conversion from 0.444 to 0.751 THz when the incident angle of the y-polarized wave is less than 30°. The II-side metamaterials can realize linear-to-linear polarization conversion from 0.668 to 0.942 THz when the incident angle of the y-polarized wave is less than 25°. Various functions can be switched freely by changing the conductivity of VO2 and the incident surface. This enables metamaterials to be used as highly sensitive sensors, optical switches, and polarization converters, which provides a new strategy for the design of composite functional metamaterials.
12
Yang, Jing Jing, Ming Huang, Jun Sun e Jun Dong Yang. "Metamaterial Sensor Based on WGM". Key Engineering Materials 495 (novembre 2011): 28–32. http://dx.doi.org/10.4028/www.scientific.net/kem.495.28.
Testo completoAbstract (sommario):
Sensor utilizing metamaterials have opened up a new field of considerable interest. We extend here the works of our group about metamaterial sensor based on Whispering Gallery Mode (WGM), which is constructed with a microring resonator sensor coated with metamaterial layer. We demonstrate that our sensor possesses higher sensitivity than the traditional sensor since the amplification and penetration of evanescent wave by metamaterials.
13
Datta, Srijan, Saptarshi Mukherjee, Xiaodong Shi, Mahmood Haq, Yiming Deng, Lalita Udpa e Edward Rothwell. "Negative Index Metamaterial Lens for Subwavelength Microwave Detection". Sensors 21, n. 14 (13 luglio 2021): 4782. http://dx.doi.org/10.3390/s21144782.
Testo completoAbstract (sommario):
Metamaterials are engineered periodic structures designed to have unique properties not encountered in naturally occurring materials. One such unusual property of metamaterials is the ability to exhibit negative refractive index over a prescribed range of frequencies. A lens made of negative refractive index metamaterials can achieve resolution beyond the diffraction limit. This paper presents the design of a metamaterial lens and its use in far-field microwave imaging for subwavelength defect detection in nondestructive evaluation (NDE). Theoretical formulation and numerical studies of the metamaterial lens design are presented followed by experimental demonstration and characterization of metamaterial behavior. Finally, a microwave homodyne receiver-based system is used in conjunction with the metamaterial lens to develop a far-field microwave NDE sensor system. A subwavelength focal spot of size 0.82λ was obtained. The system is shown to be sensitive to a defect of size 0.17λ × 0.06λ in a Teflon sample. Consecutive positions of the defect with a separation of 0.23λ was resolvable using the proposed system.
14
Xie, Xin, Xiao Ming Wang e Yu Lin Mei. "Acoustic Metamaterial Design Method Based on Green Coordinate Transformation". Materials Science Forum 976 (gennaio 2020): 15–24. http://dx.doi.org/10.4028/www.scientific.net/msf.976.15.
Testo completoAbstract (sommario):
Acoustic metamaterials have great application prospects in eliminating vibration and noise, but they are difficult to manufacture due to their anisotropy. This paper utilizes the Green coordinate transformation method to design acoustic metamaterials by combining with the transformation acoustics theory. Because the Green coordinate transformation is the pseudo-conformal mapping in three-dimensional coordinates, the anisotropy of designed metamaterials can be weakened. And also, the genetic algorithm is employed to optimize the anisotropy of metamaterials and reduce the designed metamaterial parameter difference further. Finally, the membrane-imbedded-type metamaterial is applied to realize the design and to illustrate the effectiveness of the proposed method by manipulating the acoustic wave propagation path.
15
Bang, Sanghun, Jeonghyun Kim, Gwanho Yoon, Takuo Tanaka e Junsuk Rho. "Recent Advances in Tunable and Reconfigurable Metamaterials". Micromachines 9, n. 11 (31 ottobre 2018): 560. http://dx.doi.org/10.3390/mi9110560.
Testo completoAbstract (sommario):
Metamaterials are composed of nanostructures, called artificial atoms, which can give metamaterials extraordinary properties that cannot be found in natural materials. The nanostructures themselves and their arrangements determine the metamaterials’ properties. However, a conventional metamaterial has fixed properties in general, which limit their use. Thus, real-world applications of metamaterials require the development of tunability. This paper reviews studies that realized tunable and reconfigurable metamaterials that are categorized by the mechanisms that cause the change: inducing temperature changes, illuminating light, inducing mechanical deformation, and applying electromagnetic fields. We then provide the advantages and disadvantages of each mechanism and explain the results or effects of tuning. We also introduce studies that overcome the disadvantages or strengthen the advantages of each classified tunable metamaterial.
16
Gao, Shanshi, Weidong Liu, Liangchi Zhang e Asit Kumar Gain. "A New Polymer-Based Mechanical Metamaterial with Tailorable Large Negative Poisson’s Ratios". Polymers 12, n. 7 (3 luglio 2020): 1492. http://dx.doi.org/10.3390/polym12071492.
Testo completoAbstract (sommario):
Mechanical metamaterials have attracted significant attention due to their programmable internal structure and extraordinary mechanical properties. However, most of them are still in their prototype stage without direct applications. This research developed an easy-to-use mechanical metamaterial with tailorable large negative Poisson’s ratios. This metamaterial was microstructural, with cylindrical-shell-based units and was manufactured by the 3D-printing technique. It was found numerically that the present metamaterial could achieve large negative Poisson’s ratios up to −1.618 under uniaxial tension and −1.657 under uniaxial compression, and the results of the following verification tests agreed with simulation findings. Moreover, stress concentration in this new metamaterial is much smaller than that in most of existing re-entrance metamaterials.
17
Fitzgerald, Thomas M., e Michael A. Marciniak. "Full Optical Scatter Analysis for Novel Photonic and Infrared Metamaterials". Advances in Science and Technology 75 (ottobre 2010): 240–45. http://dx.doi.org/10.4028/www.scientific.net/ast.75.240.
Testo completoAbstract (sommario):
Artificial structures with sub-optical wavelength features are engineered to feature non-conventional values for material properties such as optical and infrared permeability and permittivity. Such artificial structures are referred to as optical and infrared metamaterials.[1] The application space of electromagnetic metamaterials includes novel sub-wavelength waveguides and antennas, true time delay devices, optical filters, and plasmonic electronic-optical interfaces.[2] In this paper presents an optical diagnostic technique adapted for measuring and analyzing bidirectional polarimetric scatter from novel photonic and infrared metamaterials of interest. This optical diagnostic technique is also broadly applicable to other optical/infrared metamaterial structures that are proposed or developed in the future. The specific project goals are a) Demonstrate a novel metamaterial characterization full-polarimetric diffuse ellipsometry technique suitable to measure desired material properties with stated uncertainty limits for novel photonic and infrared metamaterials of interest. b) Demonstrate incorporation of predictive computational codes that estimate the electro-magnetic property values for metamaterial designs and concepts of interest.
18
Smolyaninov, Igor I., e Vera N. Smolyaninova. "Metamaterial superconductors". Nanophotonics 7, n. 5 (24 maggio 2018): 795–818. http://dx.doi.org/10.1515/nanoph-2017-0115.
Testo completoAbstract (sommario):
AbstractSearching for natural materials exhibiting larger electron-electron interactions constitutes a traditional approach to high-temperature superconductivity research. Very recently, we pointed out that the newly developed field of electromagnetic metamaterials deals with the somewhat related task of dielectric response engineering on a sub-100-nm scale. Considerable enhancement of the electron-electron interaction may be expected in such metamaterial scenarios as in epsilon near-zero (ENZ) and hyperbolic metamaterials. In both cases, dielectric function may become small and negative in substantial portions of the relevant four-momentum space, leading to enhancement of the electron pairing interaction. This approach has been verified in experiments with aluminum-based metamaterials. Metamaterial superconductor with Tc=3.9 K have been fabricated, which is three times that of pure aluminum (Tc=1.2 K), which opens up new possibilities to improve the Tc of other simple superconductors considerably. Taking advantage of the demonstrated success of this approach, the critical temperature of hypothetical niobium, MgB2- and H2S-based metamaterial superconductors is evaluated. The MgB2-based metamaterial superconductors are projected to reach the liquid nitrogen temperature range. In the case of an H2S-based metamaterial, the projected Tc appears to reach ~250 K.
19
Gao, Xu, Jiyuan Wei, Jiajing Huo, Zhishuai Wan e Ying Li. "The Vibration Isolation Design of a Re-Entrant Negative Poisson’s Ratio Metamaterial". Applied Sciences 13, n. 16 (21 agosto 2023): 9442. http://dx.doi.org/10.3390/app13169442.
Testo completoAbstract (sommario):
An improved re-entrant negative Poisson’s ratio metamaterial based on a combination of 3D printing and machining is proposed. The improved metamaterial exhibits a superior load-carrying and vibration isolation capacity compared to its traditional counterpart. The bandgap of the proposed metamaterial can be easily tailored through various assemblies. Additionally, particle damping is introduced to enhance the diversity of bandgap design, improve structural damping performance, and achieve better vibration isolation at low and medium frequencies. An experiment and simulation were conducted to assess the static and vibration performances of the metamaterial, and consistent results were obtained. The results indicate a 300% increase in the bearing capacity of the novel structure compared to traditional structural metamaterials. Furthermore, by increasing the density of metal assemblies, a vibration-suppressing bandgap with a lower frequency and wider bandwidth can be achieved. The introduction of particle damping significantly enhanced the vibration suppression capability of the metamaterial in the middle- and low-frequency range, effectively suppressing resonance peaks. This paper establishes a vibration design method for re-entrant metamaterials, which is experimentally validated and provides a foundation for the vibration suppression design of metamaterials.
20
Yuchao, Ma, Mo Juan, Xu Ke, Li Xiang e Sun Xinbo. "Material Parameters Acquisition and Sound Insulation Performance analysis of Membrane-type Acoustic Metamaterials Applied for Transformer". E3S Web of Conferences 136 (2019): 01031. http://dx.doi.org/10.1051/e3sconf/201913601031.
Testo completoAbstract (sommario):
As a light-weight and ultra-thin artificial material, acoustic metamaterial have more different attributes than natural material. The study of sound insulation for acoustic metamaterial is hot, and the membrane-type acoustic metamaterials supplement the deficiency of linear sound insulation materials. The physical material parameters (young modulus and loss factors)of base material of membrane-type acoustic metamaterials (PVC) is obtained by cantilever beam dynamic measurement method. The acoustic metamaterial sound insulation analysis is simulated by CAE method based on the material parameters that measured. The configuration of the simulation accuracy is measured on impedance tube, and the design work of the acoustic metamaterial sound insulation for transformer is provided. The relationship between sound insulation and the mass on membrane-type acoustic metamaterial at the different frequencies (100Hz to 500Hz) provides the reference to set sound insulation frequency.
21
Vangelatos, Z., K. Komvopoulos e CP Grigoropoulos. "Vacancies for controlling the behavior of microstructured three-dimensional mechanical metamaterials". Mathematics and Mechanics of Solids 24, n. 2 (29 novembre 2018): 511–24. http://dx.doi.org/10.1177/1081286518810739.
Testo completoAbstract (sommario):
Mechanical metamaterials are designed to exhibit enhanced properties not found in natural materials or to bolster the properties of existing materials. The theoretical foundations for tuning the mechanical properties have been established, including topological states, controllable buckling behavior, and quasi-two-dimensional mechanical metamaterials with structures containing vacancies. However, the fabrication and experimental procedures to study these structures at the microscale have not been developed yet and the three-dimensional (3D) architectures examined to date are fairly limited. In this study, 3D mechanical metamaterial structures with select unit cells designed to have vacancies were fabricated by multi-photon lithography, having as the principal objective to control (localize) failure and increase the strain energy capacity of the structure. The metamaterial structure from which all the current designs originate is the octet-truss structure, one of the most widely studied 3D metamaterials. The design of the structures was inspired by the role of vacancies in crystal lattices. Vacancies were introduced in the metamaterial structures to allow localized buckling of lattice members to occur in specific unit cells. The significant increase of the strain energy dissipated in these metamaterials is demonstrated by nanoindentation experiments and finite element results. Vacancy effects on the dynamic response of metamaterial structures are also examined in the light of modal analysis simulations. The findings of this study illustrate the importance of strategically placing vacancies in the microlattices of metamaterial structures to control the overall mechanical behavior and greatly increase strain energy dissipation.
22
Zeng, Yi, Liyun Cao, Sheng Wan, Tong Guo, Shuowei An, Yan-Feng Wang, Qiu-Jiao Du, Brice Vincent, Yue-Sheng Wang e Badreddine Assouar. "Inertially amplified seismic metamaterial with an ultra-low-frequency bandgap". Applied Physics Letters 121, n. 8 (22 agosto 2022): 081701. http://dx.doi.org/10.1063/5.0102821.
Testo completoAbstract (sommario):
In last two decades, it has been theoretically and experimentally demonstrated that seismic metamaterials are capable of isolating seismic surface waves. Inertial amplification mechanisms with small mass have been proposed to design metamaterials to isolate elastic waves in rods, beams, and plates at low frequencies. In this Letter, we propose an alternative type of seismic metamaterial providing an ultra-low-frequency bandgap induced by inertial amplification. A unique kind of inertially amplified metamaterial is first conceived and designed. Its bandgap characteristics for flexural waves are then numerically and experimentally demonstrated. Finally, the embedded inertial amplification mechanism is introduced on a soil substrate to design a seismic metamaterial capable of strongly attenuating seismic surface waves around a frequency of 4 Hz. This work provides a promising alternative way to conceive seismic metamaterials to steer and control surface waves.
23
Lan, Jun, Yunpeng Liu, Tao Wang, Yifeng Li e Xiaozhou Liu. "Acoustic coding metamaterial based on non-uniform Mie resonators". Applied Physics Letters 120, n. 16 (18 aprile 2022): 163501. http://dx.doi.org/10.1063/5.0071897.
Testo completoAbstract (sommario):
Acoustic coding metamaterials have important applications in simplifying design procedure and providing a flexible approach to realize complicated functions. Here, we design a 1-bit coding metamaterial for flexibly manipulating the sound propagation path. The capability of subwavelength acoustic propagation control on coding metamaterial is attributed to the dipole-like characteristic of the Mie resonator. The Mie resonator with a subwavelength scale is constructed with a non-uniform structure, which can generate Mie resonance with dipole-like characteristic. Two kinds of coding elements are introduced by horizontally or vertically reversing the Mie resonator in each element. To verify the performance of the designed coding metamaterials, three specific metamaterial patterns are fabricated to give different trajectories of sound propagation. Our finding may open an avenue for designing acoustic metamaterials and is expected to design intelligent acoustic devices with exciting reconfigurable and programmable applications.
24
Zhai, Zirui, Yong Wang e Hanqing Jiang. "Origami-inspired, on-demand deployable and collapsible mechanical metamaterials with tunable stiffness". Proceedings of the National Academy of Sciences 115, n. 9 (12 febbraio 2018): 2032–37. http://dx.doi.org/10.1073/pnas.1720171115.
Testo completoAbstract (sommario):
Origami has been employed to build deployable mechanical metamaterials through folding and unfolding along the crease lines. Deployable metamaterials are usually flexible, particularly along their deploying and collapsing directions, which unfortunately in many cases leads to an unstable deployed state, i.e., small perturbations may collapse the structure along the same deployment path. Here we create an origami-inspired mechanical metamaterial with on-demand deployability and selective collapsibility through energy analysis. This metamaterial has autonomous deployability from the collapsed state and can be selectively collapsed along two different paths, embodying low stiffness for one path and substantially high stiffness for another path. The created mechanical metamaterial yields load-bearing capability in the deployed direction while possessing great deployability and collapsibility. The principle in this work can be utilized to design and create versatile origami-inspired mechanical metamaterials that can find many applications.
25
Karimi Mahabadi, Rayehe, Taha Goudarzi, Romain Fleury, Bakhtiyar Orazbayev e Reza Naghdabadi. "Effect of mechanical nonlinearity on the electromagnetic response of a microwave tunable metamaterial". Journal of Physics D: Applied Physics 55, n. 20 (17 febbraio 2022): 205102. http://dx.doi.org/10.1088/1361-6463/ac5209.
Testo completoAbstract (sommario):
Abstract Tunable metamaterials functionalities change in response to external stimuli. Mechanical deformation is known to be an efficient approach to tune the electromagnetic response of a deformable metamaterial. However, in the case of large mechanical deformations, which are usually required to fully exploit the potential of the tunable metamaterials, the linear elastic mechanical analysis is no longer suitable. Nevertheless, nonlinear mechanical analysis is missing in the studies of mechanically tunable metamaterials. In this paper, we study the importance of considering nonlinearity in mechanical behavior when analyzing the response of a deformable metamaterial and its effects on electromagnetic behavior. We consider a microwave metamaterial formed by copper four-cut split ring resonators on a Polydimethylsiloxane (PDMS) substrate. Applying both displacement and force stimuli, we show that when the deformation is large, more than 10 percent strain, the use of nonlinear analysis considering the geometrical and material nonlinearities is imperative. We further show that the discrepancies between the linear and nonlinear analyses appear in overestimating the stress, underestimating the tunability of the metamaterial responses, and mispredicting the negative permeability regions.
26
Liu, Xiajun, Feng Xia, Mei Wang, Jian Liang e Maojin Yun. "Working Mechanism and Progress of Electromagnetic Metamaterial Perfect Absorber". Photonics 10, n. 2 (14 febbraio 2023): 205. http://dx.doi.org/10.3390/photonics10020205.
Testo completoAbstract (sommario):
Electromagnetic metamaterials are artificial subwavelength composites with periodic structures, which can interact strongly with the incident light to achieve effective control of the light field. Metamaterial absorbers can achieve nearly 100% perfect absorption of incident light at a specific frequency, so they are widely used in sensors, optical switches, communication, and other fields. Based on the development history of metamaterials, this paper discusses the research background and significance of metamaterial perfect absorbers. Some perfect absorption mechanisms, such as impedance matching and coherent perfect absorption, are discussed. According to the functional division, the narrowband, dual frequency, multi-frequency, broadband, and tunable metamaterial perfect absorbers are briefly described.
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Deery, Daniel, Lara Flanagan, Gordon O’Brien, Henry J. Rice e John Kennedy. "Efficient Modelling of Acoustic Metamaterials for the Performance Enhancement of an Automotive Silencer". Acoustics 4, n. 2 (1 aprile 2022): 329–44. http://dx.doi.org/10.3390/acoustics4020020.
Testo completoAbstract (sommario):
Significant potential for acoustic metamaterials to provide a breakthrough in sound attenuation has been unlocked in recent times due to advancements in additive manufacturing techniques. These materials allow the targeting of specific frequencies for sound attenuation. To date, acoustic metamaterials have not been demonstrated in a commercial automotive silencer for performance enhancement. A significant obstacle to the practical use of acoustic metamaterials is the need for low cost and efficient modelling strategies in the design phase. This study investigates the effect of acoustic metamaterials within a representative automotive silencer. The acoustic metamaterial design is achieved using a combination of analytical and finite element models, validated by experiment. The acoustic metamaterial is then compared with commonly used techniques in the silencer industry to gauge the effectiveness of the acoustic metamaterials. COMSOL simulations were used to validate the developed test rig and were compared to experimental results which were obtained using the two-load transmission loss test method. Through this testing method, the implementation of a labyrinthine metamaterial cylinder proved to be a significant improvement in transmission loss within the silencer, with an increase in transmission loss of 40 dB at 1500 Hz. The research has successfully shown that acoustic metamaterials can be used in practical settings, such as an automotive silencer, to improve the overall sound attenuating performance. The described analytical model demonstrates the potential for industrially relevant low cost design tools.
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Saravana Jothi, N. S., e A. Hunt. "Active mechanical metamaterial with embedded piezoelectric actuation". APL Materials 10, n. 9 (1 settembre 2022): 091117. http://dx.doi.org/10.1063/5.0101420.
Testo completoAbstract (sommario):
Metamaterials are artificially structured materials and exhibit properties that are uncommon or non-existent in nature. Mechanical metamaterials show exotic mechanical properties, such as negative stiffness, vanishing shear modulus, or negative Poisson’s ratio. These properties stem from the geometry and arrangement of the metamaterial unit elements and, therefore, cannot be altered after fabrication. Active mechanical metamaterials aim to overcome this limitation by embedding actuation into the metamaterial unit elements to alter the material properties or mechanical state. This could pave the way for a variety of applications in industries, such as aerospace, robotics, and high-tech engineering. This work proposes and studies an active mechanical metamaterial concept that can actively control the force and deformation distribution within its lattice. Individually controllable actuation units are designed based on piezostack actuators and compliant mechanisms and interconnected into an active metamaterial lattice. Both the actuation units and the metamaterial lattice are modeled, built, and experimentally studied. In experiments, the actuation units attained 240 and 1510 µm extensions, respectively, in quasi-static and resonant operation at 81 Hz, and 0.3 N blocked force at frequencies up to 100 Hz. Quasi-static experiments on the active metamaterial lattice prototype demonstrated morphing into four different configurations: Tilt left, tilt right, convex, and concave profiles. This demonstrated the feasibility of altering the force and deformation distribution within the mechanical metamaterial lattice. Much more research is expected to follow in this field since the actively tuneable mechanical state and properties can enable qualitatively new engineering solutions.
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Yan, Dexian, Yi Wang, Yu Qiu, Qinyin Feng, Xiangjun Li, Jining Li, Guohua Qiu e Jiusheng Li. "A Review: The Functional Materials-Assisted Terahertz Metamaterial Absorbers and Polarization Converters". Photonics 9, n. 5 (11 maggio 2022): 335. http://dx.doi.org/10.3390/photonics9050335.
Testo completoAbstract (sommario):
When metamaterial structures meet functional materials, what will happen? The recent rise of the combination of metamaterial structures and functional materials opens new opportunities for dynamic manipulation of terahertz wave. The optical responses of functional materials are greatly improved based on the highly-localized structures in metamaterials, and the properties of metamaterials can in turn be manipulated in a wide dynamic range based on the external stimulation. In the topical review, we summarize the recent progress of the functional materials-based metamaterial structures for flexible control of the terahertz absorption and polarization conversion. The reviewed devices include but are not limited to terahertz metamaterial absorbers with different characteristics, polarization converters, wave plates, and so on. We review the dynamical tunable metamaterial structures based on the combination with functional materials such as graphene, vanadium dioxide (VO2) and Dirac semimetal (DSM) under various external stimulation. The faced challenges and future prospects of the related researches will also be discussed in the end.
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Machac, Jan. "A negative permittivity metamaterial composed of planar resonators with randomly detuned resonant frequencies and randomly distributed in space". International Journal of Microwave and Wireless Technologies 10, n. 9 (4 luglio 2018): 1028–34. http://dx.doi.org/10.1017/s1759078718001046.
Testo completoAbstract (sommario):
AbstractThis paper investigates metamaterials composed of resonant particles with negative electric polarizability located in a three-dimensional net. The main problem in fabricating these materials is the spread of the resonant frequencies of particular planar resonators. This spread is caused by the tolerances of the fabrication process for planar resonators. The simulation shows that there is a limit to the dispersion of resonant frequencies that allow the metamaterial to behave as a metamaterial with negative effective permittivity. Two metamaterials with a negative real part of the effective permittivity were designed on the basis of simulations. The first metamaterial has a regular periodic structure. The second is a metamaterial in which the resonant particles are randomly distributed both in space and in orientation, and it offers an isotropic response. This metamaterial was fabricated by inserting planar resonators into plastic shells that can be poured into any volume and ensure a random distribution of the resonant particles in space. The results of the simulations have been verified by measurements.
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Choi, Jung Sik, e Gil Ho Yoon. "An Acoustic Hyperlens with Negative Direction Based on Double Split Hollow Sphere". Journal of Theoretical and Computational Acoustics 27, n. 02 (giugno 2019): 1850025. http://dx.doi.org/10.1142/s2591728518500251.
Testo completoAbstract (sommario):
This study develops a new acoustic negative-refraction metamaterial that utilizes a synthesized double split hollow sphere (DSHS) for its unit cell. Recent relevant research has affirmed the concept that acoustic metamaterials can show unusual behavior that has not been observed in nature previously. However, as some hypothetical metamaterial designs have material properties not found in nature, the realization of practical metamaterials requires practical and complicated models. As a contribution to the development of acoustic metamaterials, the present study proposes a new anisotropic unit structure that encompasses Helmholtz resonators. This structure is referred to as the DSHS, is easy to manufacture, and has the advantage in that it uses the natural medium in its original form. By drawing the equifrequency or isofrequency contours of the designed two-dimensional (2D) anisotropic unit structure using the Floquet–Bloch’s principle, the properties of the present metamaterial can be understood. Numerical simulations are also conducted to identify and present the characteristics of the presented acoustic metamaterial. Through these, a new refraction phenomenon is identified that deviates from Snell’s law, and an acoustic hyperlens is numerically implemented that overcomes the diffraction limit.
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Fan, Yuancheng, Xuan He, Fuli Zhang, Weiqi Cai, Chang Li, Quanhong Fu, Nataliia V. Sydorchuk e Sergey L. Prosvirnin. "Fano-Resonant Hybrid Metamaterial for Enhanced Nonlinear Tunability and Hysteresis Behavior". Research 2021 (13 agosto 2021): 1–9. http://dx.doi.org/10.34133/2021/9754083.
Testo completoAbstract (sommario):
Artificial resonant metamaterial with subwavelength localized filed is promising for advanced nonlinear photonic applications. In this article, we demonstrate enhanced nonlinear frequency-agile response and hysteresis tunability in a Fano-resonant hybrid metamaterial. A ceramic cuboid is electromagnetically coupled with metal cut-wire structure to excite the high-Q Fano-resonant mode in the dielectric/metal hybrid metamaterial. It is found that the significant nonlinear response of the ceramic cuboid can be employed for realization of tunable metamaterials by exciting its magnetic mode, and the trapped mode with an asymmetric Fano-like resonance is beneficial to achieve notable nonlinear modulation on the scattering spectrum. The nonlinear tunability of both the ceramic structure and the ceramic/metal hybrid metamaterial is promising to extend the operation band of metamaterials, providing possibility in practical applications with enhanced light-matter interactions.
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Neil, Thomas R., Zhiyuan Shen, Daniel Robert, Bruce W. Drinkwater e Marc W. Holderied. "Moth wings are acoustic metamaterials". Proceedings of the National Academy of Sciences 117, n. 49 (23 novembre 2020): 31134–41. http://dx.doi.org/10.1073/pnas.2014531117.
Testo completoAbstract (sommario):
Metamaterials assemble multiple subwavelength elements to create structures with extraordinary physical properties (1–4). Optical metamaterials are rare in nature and no natural acoustic metamaterials are known. Here, we reveal that the intricate scale layer on moth wings forms a metamaterial ultrasound absorber (peak absorption = 72% of sound intensity at 78 kHz) that is 111 times thinner than the longest absorbed wavelength. Individual scales act as resonant (5) unit cells that are linked via a shared wing membrane to form this metamaterial, and collectively they generate hard-to-attain broadband deep-subwavelength absorption. Their collective absorption exceeds the sum of their individual contributions. This sound absorber provides moth wings with acoustic camouflage (6) against echolocating bats. It combines broadband absorption of all frequencies used by bats with light and ultrathin structures that meet aerodynamic constraints on wing weight and thickness. The morphological implementation seen in this evolved acoustic metamaterial reveals enticing ways to design high-performance noise mitigation devices.
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Zhou, Ying, Hao Li, Mengli Ye, Yun Shi e Liang Gao. "Novel Design Scheme for Structural Fundamental Frequency of Porous Acoustic Metamaterials". Materials 15, n. 19 (22 settembre 2022): 6569. http://dx.doi.org/10.3390/ma15196569.
Testo completoAbstract (sommario):
Structural resonance increases the vibration and noise of porous acoustic metamaterials while reducing the energy consumption and conversion efficiency of acoustic waves. Therefore, structural fundamental frequency of porous acoustic metamaterials is required to be controlled to avoid resonance. This study proposes a full-cycle interactive progressive (FIP) design scheme for porous acoustic metamaterials. The FIP design scheme first establishes a specific parameter relationship for the initial model based on the intentions of the designers. The initial model is then dynamically adjusted through a series of optimization processes. In particular, the FIP design scheme is developed for a porous acoustic metamaterial in an acoustic-structure interaction system. The effects of the structural parameters and applied boundary conditions of the porous acoustic metamaterial on the structural fundamental frequency are investigated. A surrogate model is introduced to reduce the calculation costs and improve the design efficiency of the parametric optimization. The frequency-modulation acoustic metamaterial is tailored to improve its acoustic and vibrational characteristics, including the resonance resistance and low dynamic response. The features of the FIP design scheme in the optimized design of porous acoustic metamaterials are demonstrated.
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Hu, Longfei, Ketian Shi, Xiaoguang Luo, Jijun Yu, Bangcheng Ai e Chao Liu. "Application of Additively Manufactured Pentamode Metamaterials in Sodium/Inconel 718 Heat Pipes". Materials 14, n. 11 (2 giugno 2021): 3016. http://dx.doi.org/10.3390/ma14113016.
Testo completoAbstract (sommario):
In this study, pentamode metamaterials were proposed for thermal stress accommodation of alkali metal heat pipes. Sodium/Inconel 718 heat pipes with and without pentamode metamaterial reinforcement were designed and fabricated. Then, these heat pipes were characterized by startup tests and thermal response simulations. It was found that pentamode metamaterial reinforcement did not affect the startup properties of sodium/Inconel 718 heat pipes. At 650–950 °C heating, there was a successful startup of heat pipes with and without pentamode metamaterial reinforcement, displaying uniform temperature distributions. A further simulation indicated that pentamode metamaterials could accommodate thermal stresses in sodium/Inconel 718 heat pipes. With pentamode metamaterial reinforcement, stresses in the heat pipes decreased from 12.9–62.1 to 10.2–52.4 MPa. As a result, sodium/Inconel 718 heat pipes could be used more confidently. This work was instructive for the engineering application of alkali metal heat pipes.
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Tonkaev, Pavel, e Sergey Makarov. "Control of spontaneous emission rate in lead halide perovskite film on hyperbolic metamaterial". Journal of Physics: Conference Series 2015, n. 1 (1 novembre 2021): 012153. http://dx.doi.org/10.1088/1742-6596/2015/1/012153.
Testo completoAbstract (sommario):
Abstract Hyperbolic metamaterials represent a class of nanophotonic architectures with the possibility of controlling density of optical states. Due to this property, hyperbolic metamaterials can be employed as meta-electrodes in optoelectronic devices. On the other hand, lead halide perovskites have several promising properties for application in light-emitting devices. Moreover, a perovskite film is easily deposited on a hyperbolic metamaterial surface. Here, we theoretically show how to accelerate radiative recombination in a perovskite film with a hyperbolic metamaterial. This effect can be applied in light-emitting devices, where radiative recombination is extremely important.
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Terao, Takamichi. "Numerical methods for design of metamaterial photonic crystals and random metamaterials". EPJ Applied Metamaterials 9 (2022): 1. http://dx.doi.org/10.1051/epjam/2021012.
Testo completoAbstract (sommario):
Two-dimensional metamaterial photonic crystals (2DMPCs) composed of dispersive metamaterials in a positive-refractive-index medium were investigated by incorporating finite-difference time-domain calculations into the auxiliary differential equation method. A distinct band gap was formed and the effects of positional and size disorder when the dispersive metamaterials are aligned in air were elucidated. In addition, using the self-consistent finite-difference frequency-domain method, an eigenmode analysis of 2DMPCs with positional disorder was performed. Finally, a numerical method for the inverse design of binary random metamaterial multilayers was proposed.
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He, Yufang, Xiangtian Kong, Juntao He, Junpu Ling e Mingyao Pi. "A novel all-metal metamaterial for constructing relativistic slow wave structure". AIP Advances 12, n. 3 (1 marzo 2022): 035345. http://dx.doi.org/10.1063/5.0083360.
Testo completoAbstract (sommario):
In recent vacuum electronic devices, metamaterials have shown an obvious advantage of miniaturization. Due to increasing miniaturization demand, research of metamaterials in high-power microwave (HPM) field is now also a hotspot. For better applications of metamaterials, there are still two issues to be solved, the low space limit current of the structure and the low uniformity of the working electric field. To solve these problems, we construct a novel all-metal metamaterial structure by applying a 45° rotational arrangement in space and a four-support rod structure. This new metamaterial structure has a great uniformity of the axis electric field, and its electric field fluctuation is reduced from 8.6% to 2.8%. Based on this metamaterial structure, we proposed a novel relativistic slow wave structure, and its working mode has a negative dispersion characteristic. Using the method of expanding the electron beam channel, the space limit current of the relativistic slow wave structure is greatly improved to 12.3 kA, and the particle simulation method is used to prove the increase in the space limit current. In addition, it is found that this slow wave structure has higher coupling impedance, which provides a better working environment for an annular relativistic electron beam. Therefore, this metamaterial structure has great potential in the HPM field.
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Xu, Rui-Jia, e Yu-Sheng Lin. "Actively MEMS-Based Tunable Metamaterials for Advanced and Emerging Applications". Electronics 11, n. 2 (13 gennaio 2022): 243. http://dx.doi.org/10.3390/electronics11020243.
Testo completoAbstract (sommario):
In recent years, tunable metamaterials have attracted intensive research interest due to their outstanding characteristics, which are dependent on the geometrical dimensions rather than the material composition of the nanostructure. Among tuning approaches, micro-electro-mechanical systems (MEMS) is a well-known technology that mechanically reconfigures the metamaterial unit cells. In this study, the development of MEMS-based metamaterial is reviewed and analyzed based on several types of actuators, including electrothermal, electrostatic, electromagnetic, and stretching actuation mechanisms. The moveable displacement and driving power are the key factors in evaluating the performance of actuators. Therefore, a comparison of actuating methods is offered as a basic guideline for selecting micro-actuators integrated with metamaterial. Additionally, by exploiting electro-mechanical inputs, MEMS-based metamaterials make possible the manipulation of incident electromagnetic waves, including amplitude, frequency, phase, and the polarization state, which enables many implementations of potential applications in optics. In particular, two typical applications of MEMS-based tunable metamaterials are reviewed, i.e., logic operation and sensing. These integrations of MEMS with metamaterial provide a novel route for the enhancement of conventional optical devices and exhibit great potentials in innovative applications, such as intelligent optical networks, invisibility cloaks, photonic signal processing, and so on.
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Enaki, Nicolae A., Ion Munteanu, Tatiana Paslari, Marina Turcan, Elena Starodub, Sergiu Bazgan, Diana Podoleanu et al. "Topological Avenue for Efficient Decontamination of Large Volumes of Fluids via UVC Irradiation of Packed Metamaterials". Materials 16, n. 13 (24 giugno 2023): 4559. http://dx.doi.org/10.3390/ma16134559.
Testo completoAbstract (sommario):
Nowadays, metamaterials application enjoys notoriety in fluid decontamination and pathogen annihilation, which are frequently present in polluted fluids (e.g., water, blood, blood plasma, air or other gases). The depollution effect is largely enhanced by UVC irradiation. The novelty of this contribution comes from the significant increase by packing of the total surface of metamaterials in contact with contaminated fluids. Packed metamaterial samples are subjected to UVC irradiation, with expected advantages for implant sterilization and long-term prevention of nosocomial infections over large clinical areas. The novel aspect of the investigation consists of a combination of big and small elements of the metamaterial to optimize the above effects connected with fluids and irradiation. The big elements allow the radiation to penetrate deep inside the fluid, and the small elements optimally disperse this radiation toward deeper regions of the metamaterial. A packing scheme of smaller, in-between large metamaterial spheres and fibres is proposed for promoting enhanced depollution against pathogen agents. It is demonstrated that the total surface of metamaterials in contact with contaminated fluids/surface is significantly increased as a result of packing. This opens, in our opinion, new auspicious perspectives in the construction of novel equipment with high sensibility in the detection and decontamination of microorganisms.
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He, Jingwen, Xunjun He, Tao Dong, Sen Wang, Maixia Fu e Yan Zhang. "Recent progress and applications of terahertz metamaterials". Journal of Physics D: Applied Physics 55, n. 12 (12 novembre 2021): 123002. http://dx.doi.org/10.1088/1361-6463/ac3282.
Testo completoAbstract (sommario):
Abstract Metamaterials are an artificial electromagnetic material composed of periodic/non-periodic subwavelength micro-/nanostructures, i.e. meta-atoms. The meta-atom interacts with the incident electromagnetic wave and introduces electromagnetic resonance, which makes the metamaterial exhibit the desired electromagnetic characteristics. Therefore, the electromagnetic wave can be controlled by changing the geometry, configuration and distribution of the meta-atoms. Due to their flexible electromagnetic manipulation ability, metamaterials have attracted great interest in many fields, such as super-resolution imaging, high-sensitive detection, aerocraft stealth and laser-machining. A planar metamaterial with one or a few layers of meta-atoms is called a metasurface. The metasurface can not only manipulate the amplitude, phase and polarization of the electromagnetic waves, but also has the advantages of being ultra-thin, ultra-light and easy to process. In the terahertz (THz) region, more and more devices based on metasurfaces have been proposed for spectrum modulation and wavefront shaping, which has contributed to the rapid development of THz technology. This paper reviews the design principles and research progress of metamaterials/metasurfaces for spectrum modulation, wavefront shaping, polarization conversion and surface wave manipulation in the THz region. Active metamaterials can be used to manipulate electromagnetic waves dynamically, and this will become a research field with great application potential. In this review, the implementation schemes and research results of various active THz metamaterial devices are reviewed in detail. Furthermore, the potential applications of metamaterials/metasurfaces in security, high-capacity communication, biomedicine and other fields are analyzed. Finally, we discuss the future developments and challenges of THz metamaterials.
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LeGrande, Joshua, Mohammad Bukhari e Oumar Barry. "Effect of electromechanical coupling on locally resonant quasiperiodic metamaterials". AIP Advances 13, n. 1 (1 gennaio 2023): 015112. http://dx.doi.org/10.1063/5.0119914.
Testo completoAbstract (sommario):
Electromechanical metamaterials have been the focus of many recent studies for use in simultaneous energy harvesting and vibration control. Metamaterials with quasiperiodic patterns possess many useful topological properties that make them a good candidate for study. However, it is currently unknown what effect electromechanical coupling may have on the topological bandgaps and localized edge modes of a quasiperiodic metamaterial. In this paper, we study a quasiperiodic metamaterial with electromechanical resonators to investigate the effect on its bandgaps and localized vibration modes. We derive here the analytical dispersion surfaces of the proposed metamaterial. A semi-infinite system is also simulated numerically to validate the analytical results and show the band structure for different quasiperiodic patterns, load resistors, and electromechanical coupling coefficients. The topological nature of the bandgaps is detailed through an estimation of the integrated density of states. Furthermore, the presence of topological edge modes is determined through numerical simulation of the energy harvested from the system. The results indicate that quasiperiodic metamaterials with electromechanical resonators can be used for effective energy harvesting without changes in the bandgap topology for weak electromechanical coupling.
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Xi, Zhipeng, Xiaochi Lu, Tongsheng Shen, Chunrong Zou, Li Chen e Shaojun Guo. "Research on Design Method of Multilayer Metamaterials Based on Stochastic Topology". Materials 16, n. 15 (25 luglio 2023): 5229. http://dx.doi.org/10.3390/ma16155229.
Testo completoAbstract (sommario):
Metamaterials are usually designed using biomimetic technology based on natural biological characteristics or topology optimization based on prior knowledge. Although satisfactory results can be achieved to a certain extent, there are still many performance limitations. For overcoming the above limitations, this paper proposes a rapid metamaterials design method based on the generation of random topological patterns. This method realizes the combined big data simulation and structure optimization of structure-electromagnetic properties, which makes up for the shortcomings of traditional design methods. The electromagnetic properties of the proposed metamaterials are verified by experiments. The reflection coefficient of the designed absorbing metamaterial unit is all lower than −15 dB over 12–16 GHz. Compared with the metal floor, the radar cross section (RCS) of the designed metamaterial is reduced by a minimum of 14.5 dB and a maximum of 27.6 dB over the operating band. The performance parameters of metamaterial obtained based on the random topology design method are consistent with the simulation design results, which further verifies the reliability of the algorithm in this paper.
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Hedayati, Reza, e Sandhya Lakshmanan. "Pneumatically-Actuated Acoustic Metamaterials Based on Helmholtz Resonators". Materials 13, n. 6 (23 marzo 2020): 1456. http://dx.doi.org/10.3390/ma13061456.
Testo completoAbstract (sommario):
Metamaterials are periodic structures which offer physical properties not found in nature. Particularly, acoustic metamaterials can manipulate sound and elastic waves both spatially and spectrally in unpreceded ways. Acoustic metamaterials can generate arbitrary acoustic bandgaps by scattering sound waves, which is a superior property for insulation properties. In this study, one dimension of the resonators (depth of cavity) was altered by means of a pneumatic actuation system. To this end, metamaterial slabs were additively manufactured and connected to a proportional pressure control unit. The noise reduction performance of active acoustic metamaterials in closed- and open-space configurations was measured in different control conditions. The pneumatic actuation system was used to vary the pressure behind pistons inside each cell of the metamaterial, and as a result to vary the cavity depth of each unit cell. Two pressures were considered, P = 0.05 bar, which led to higher depth of the cavities, and P = 0.15 bar, which resulted in lower depth of cavities. The results showed that by changing the pressure from P = 0.05 (high cavity depth) to P = 0.15 (low cavity depth), the acoustic bandgap can be shifted from a frequency band of 150–350 Hz to a frequency band of 300–600 Hz. The pneumatically-actuated acoustical metamaterial gave a peak attenuation of 20 dB (at 500 Hz) in the closed system and 15 dB (at 500 Hz) in the open system. A step forward would be to tune different unit cells of the metamaterial with different pressure levels (and therefore different cavity depths) in order to target a broader range of frequencies.
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Khodaei, Mohammad Javad, Amin Mehrvarz, Reza Ghaffarivardavagh e Nader Jalili. "Retrieving effective acoustic impedance and refractive index for size mismatch samples". AIP Advances 12, n. 6 (1 giugno 2022): 065224. http://dx.doi.org/10.1063/5.0082371.
Testo completoAbstract (sommario):
In this paper, we have presented an analytical solution to extract the effective properties of acoustic metamaterials from the measured complex transmission and reflection coefficients when the metamaterial and impedance tube have different sizes. We first considered the air gap as a separate domain and modeled the problem as a bilayer metamaterial inside a duct. Then, we established theoretically that when the dimensions of an acoustic metamaterial are known, the effective properties may be derived by solving a set of eight linear equations. Finally, we assessed the proposed technique using numerical simulation data. The proposed method is shown to calculate the effective refractive index and impedance with an error of less than 1%. This method provides an efficient approach to analyze the effective properties of acoustic metamaterials of different sizes.
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Zhu, Lei, e Liang Dong. "Electromagnetically induced transparency metamaterials: theories, designs and applications". Journal of Physics D: Applied Physics 55, n. 26 (6 aprile 2022): 263003. http://dx.doi.org/10.1088/1361-6463/ac60cc.
Testo completoAbstract (sommario):
Abstract Electromagnetically induced transparency (EIT) stems from a quantum system, where an opaque atomic medium appears the narrow transparent state within a wide absorption area. This phenomenon can be achieved by quantum interference of pumping light and detecting light at different energy levels of transitions. In the generation process of EIT effect, in addition to transparent state, the atomic medium is usually accompanied with a strong dispersion effect, which will bright about a significant reduction of light velocity, thus realizing many important applications, such as slow light propagations. Although the EIT effect has many important applications, its application scenarios are greatly limited due to the fact that EIT realization usually requires specific and complicated conditions, such as refrigeration temperature, high intensity laser, etc. Recently, the analogue of EIT effect in metamaterial has attracted increasing attentions due to its advantages such as controllable room temperature and large operating bandwidth. Metamaterial analogue of EIT effect has become a new research focus. In this article, we review current research progresses on EIT metamaterials. Firstly, we describe the theoretical models for analyzing EIT metamaterials, including the mechanical oscillator model and the equivalent circuit model. Then, we describe the simulations, designs and experiments of passive EIT metamaterials with fixed structures and active EIT metamaterials with tunable elements. Furthermore, the applications of EIT metamaterials in the areas of slow lights, sensings, absorptions and other fields are also reviewed. Finally, the possible directions and key issues of future EIT metamaterial researches are prospected.
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Ben-Yelun, Ismael, Guillermo Gómez-Carano, Francisco J. San Millán, Miguel Ángel Sanz, Francisco Javier Montáns e Luis Saucedo-Mora. "GAM: General Auxetic Metamaterial with Tunable 3D Auxetic Behavior Using the Same Unit Cell Boundary Connectivity". Materials 16, n. 9 (29 aprile 2023): 3473. http://dx.doi.org/10.3390/ma16093473.
Testo completoAbstract (sommario):
Research on auxetic metamaterials is important due to their high performance against impact loadings and their usefulness in actuators, among other applications. These metamaterials offer a negative Poisson’s ratio at the macro level. However, usual auxetic metamaterials face challenges in (1) grading the effect, (2) coupling and combining auxetic metamaterials with non-auxetic materials due to boundary compatibility, (3) obtaining the same auxetic behavior in all directions in the transverse plane, and (4) adapting the regular geometry to the component design boundary and shape. The goal of this paper is to present a novel, recently patented tunable 3D metamaterial created to reproduce a wide spectrum of 3D auxetic and non-auxetic Poisson’s ratios and Young’s moduli. This wide range is obtained using the same basic unit cell geometry and boundary connections with neighboring cells, facilitating designs using functionally graded metamaterials as only the connectivity and position of the cell’s internal nodes are modified. Based on simple spatial triangularization, the metamaterial is easily scalable and better accommodates spatial curvatures or boundaries by changing the locations of nodes and lengths of bars.
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Slesarenko, Viacheslav. "Planar Mechanical Metamaterials with Embedded Permanent Magnets". Materials 13, n. 6 (13 marzo 2020): 1313. http://dx.doi.org/10.3390/ma13061313.
Testo completoAbstract (sommario):
The design space of mechanical metamaterials can be drastically enriched by the employment of non-mechanical interactions between unit cells. Here, the mechanical behavior of planar metamaterials consisting of rotating squares is controlled through the periodic embedment of modified elementary cells with attractive and repulsive configurations of the magnets. The proposed design of mechanical metamaterials produced by three-dimensional printing enables the efficient and quick reprogramming of their mechanical properties through the insertion of the magnets into various locations within the metamaterial. Experimental and numerical studies reveal that under equibiaxial compression various mechanical characteristics, such as buckling strain and post-buckling stiffness, can be finely tuned through the rational placement of the magnets. Moreover, this strategy is shown to be efficient in introducing bistability into the metamaterial with an initially single equilibrium state.
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Li, Zhenghong, Yuheng Liu, Yafei Wang, Haibao Lu, Ming Lei e Yong Qing Fu. "3D Printing of Auxetic Shape-Memory Metamaterial Towards Designable Buckling". International Journal of Applied Mechanics 13, n. 01 (gennaio 2021): 2150011. http://dx.doi.org/10.1142/s1758825121500113.
Testo completoAbstract (sommario):
As one of the most popular 3D printed metamaterials, the auxetic structure with its tunable Poisson’s ratio has attracted huge amount of attention recently. In this study, we designed an auxetic shape-memory metamaterial, which showed designable buckling responses by using the thermomechanically coupled in-plane instability. The influence of viscoelasticity on in-plane moduli and Poisson’s ratios of shape-memory auxetic metamaterial was experimentally investigated. Based on the generalized Maxwell model and finite-element method, the buckling behaviors and their main influence factors were studied. The analytical results and experimental ones showed a good agreement. Thermomechanical properties of the printed metamaterials govern the temperature and strain rate-dependent buckling, and a controllable transition from the negative to positive Poisson’s ratio in the metamaterials can be achieved. Based on the shape memory effect, the buckled state and the Poisson’s ratio of the metamaterials can be tuned by programmed thermomechanical processes. This study provides a simple and efficient way to generate morphing structures using the designable buckling effect.
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Jiang, Haoqing, Yue Wang, Zijian Cui, Xiaoju Zhang, Yongqiang Zhu e Kuang Zhang. "Vanadium Dioxide-Based Terahertz Metamaterial Devices Switchable between Transmission and Absorption". Micromachines 13, n. 5 (30 aprile 2022): 715. http://dx.doi.org/10.3390/mi13050715.
Testo completoAbstract (sommario):
Terahertz metamaterial plays a significant role in the development of imaging, sensing, and communications. The function of conventional terahertz metamaterials was fixed after fabrication. They can only achieve a single function and do not have adjustable characteristics, which greatly limits the scalability and practical application of metamaterial. Here, we propose a vanadium dioxide-based terahertz metamaterial device, which is switchable between being a transmitter and an absorber. The transmission and absorption characteristics and temperature tunable properties of phase change metamaterials in the terahertz band were investigated. As the temperature of vanadium dioxide is varied between 20 °C and 80 °C, the device can switch between transmission and quad-band resonance absorption at the terahertz frequency range, with a high transmission rate of over 80% and a peak absorbance of 98.3%, respectively. In addition, when the device acts as an absorber, the proposed metamaterial device is tunable, and the modulation amplitude can reach 94.3%; while the device is used as a transmissive device, the modulation amplitude of the transmission peak at 81%. The results indicate that the proposed metamaterial device can promote the applications of terahertz devices, such as switching, modulation, and sensing.