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12 pages, 1178 KiB

Open AccessArticle

Negative-Viscosity Materials: Exploiting the Effect of Negative Mass

by Edward Bormashenko and Shraga Shoval

Materials 2025, 18(6), 1199; https://doi.org/10.3390/ma18061199 - 7 Mar 2025

Viewed by 832

The research is motivated by the search for materials with negative viscosity to exploit the effect of negative mass. We introduce media (gaseous and liquid) that demonstrate negative viscosity. Consider the vibrated plate, which is vertically pulled through the ideal gas and built [...] Read more.

The research is motivated by the search for materials with negative viscosity to exploit the effect of negative mass. We introduce media (gaseous and liquid) that demonstrate negative viscosity. Consider the vibrated plate, which is vertically pulled through the ideal gas and built from the core–shell “meta-molecules”. Vibrating the vertical plate supplies an excess vertical momentum to the core–shell meta-molecules. If the frequency of vibrations is larger than the resonant frequency, the excess moment is oriented against the direction of the vertical motion; thus, the effect of negative viscosity becomes possible. The effective viscosity becomes negative when the frequency of the plate vibrations approaches the resonant frequency from above. Thus, a novel physical mechanism resulting in negative viscosity is introduced. No violation of energy conservation is observed; the energy is supplied to the system by the external source vibrating the plate. The effect of the negative viscosity is also possible in liquids. Frequency dependence of the viscosity is addressed. Asymptotic expressions are derived for the frequency-dependent viscosity. Introduced meta-materials may be exploited for the development of media with prescribed rheological properties. Possible realizations of the negative-viscosity media are discussed. Full article

(This article belongs to the Section Materials Physics)

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8 pages, 22357 KiB

Open AccessArticle

Controllable Fano-like Resonance in Terahertz Planar Meta-Rotamers

by Subin Jo, Min-Gyu Bae and Joong-Wook Lee

Appl. Sci. 2021, 11(21), 9796; https://doi.org/10.3390/app11219796 - 20 Oct 2021

Cited by 2 | Viewed by 2021

Abstract

Meta-molecules composed of meta-atoms exhibit various electromagnetic phenomena owing to the interaction among the resonance modes of the meta-atoms. In this study, we numerically investigated Fano-like-resonant planar metamaterials composed of meta-molecules at terahertz (THz) frequencies. We present meta-rotamers based only on the difference [...] Read more.

Meta-molecules composed of meta-atoms exhibit various electromagnetic phenomena owing to the interaction among the resonance modes of the meta-atoms. In this study, we numerically investigated Fano-like-resonant planar metamaterials composed of meta-molecules at terahertz (THz) frequencies. We present meta-rotamers based only on the difference in the spatial position of their component meta-atoms (C- and Y-shapes) that can be interconverted by rotations and have tunable Fano-like resonance. This is because of the cooperative effects determined by the spatial coupling conditions of the nodes and antinodes of electric-dipole and inductive–capacitive (LC) resonances of the meta-atoms. The findings of this study provide potential options for exploring novel THz devices and for engineering high-level functionalities in metamaterial-based devices. Full article

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15 pages, 2500 KiB

Open AccessReview

Research Progress and Development Trends of Acoustic Metamaterials

by Hao Song, Xiaodong Ding, Zixian Cui and Haohao Hu

Molecules 2021, 26(13), 4018; https://doi.org/10.3390/molecules26134018 - 30 Jun 2021

Cited by 26 | Viewed by 5801

Abstract

Acoustic metamaterials are materials with artificially designed structures, which have characteristics that surpass the behavior of natural materials, such as negative refraction, anomalous Doppler effect, plane focusing, etc. This article mainly introduces and summarizes the related research progress of acoustic metamaterials in the [...] Read more.

Acoustic metamaterials are materials with artificially designed structures, which have characteristics that surpass the behavior of natural materials, such as negative refraction, anomalous Doppler effect, plane focusing, etc. This article mainly introduces and summarizes the related research progress of acoustic metamaterials in the past two decades, focusing on meta-atomic acoustic metamaterials, metamolecular acoustic metamaterials, meta-atomic clusters and metamolecule cluster acoustic metamaterials. Finally, the research overview and development trend of acoustic metasurfaces are briefly introduced. Full article

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13 pages, 3886 KiB

Open AccessArticle

Multiple Fano Resonances with Tunable Electromagnetic Properties in Graphene Plasmonic Metamolecules

by Hengjie Zhou, Shaojian Su, Weibin Qiu, Zeyang Zhao, Zhili Lin, Pingping Qiu and Qiang Kan

Nanomaterials 2020, 10(2), 236; https://doi.org/10.3390/nano10020236 - 29 Jan 2020

Cited by 10 | Viewed by 3198

Abstract

Multiple Fano resonances (FRs) can be produced by destroying the symmetry of structure or adding additional nanoparticles without changing the spatial symmetry, which has been proved in noble metal structures. However, due to the disadvantages of low modulation depth, large damping rate, and [...] Read more.

Multiple Fano resonances (FRs) can be produced by destroying the symmetry of structure or adding additional nanoparticles without changing the spatial symmetry, which has been proved in noble metal structures. However, due to the disadvantages of low modulation depth, large damping rate, and broadband spectral responses, many resonance applications are limited. In this research paper, we propose a graphene plasmonic metamolecule (PMM) by adding an additional 12 nanodiscs around a graphene heptamer, where two Fano resonance modes with different wavelengths are observed in the extinction spectrum. The competition between the two FRs as well as the modulation depth of each FR is investigated by varying the materials and the geometrical parameters of the nanostructure. A simple trimer model, which emulates the radical distribution of the PMM, is employed to understand the electromagnetic field behaviors during the variation of the parameters. Our proposed graphene nanostructures might find significant applications in the fields of single molecule detection, chemical or biochemical sensing, and nanoantenna. Full article

(This article belongs to the Section Nanocomposite Materials)

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8 pages, 4861 KiB

Open AccessArticle

Adjusting Electric Field Intensity Using Hybridized Dielectric Metamolecule

by Haohua Li, Xiaobo Wang and Ji Zhou

Symmetry 2019, 11(10), 1285; https://doi.org/10.3390/sym11101285 - 14 Oct 2019

Viewed by 2099

Abstract

In this paper, we report on achieving the hybridization effect in a Mie-based dielectric metamolecule and provide its physically intuitive picture. Hybridization results in the splitting of the initial overlapping resonance dips, thus leading to two new collective resonance modes. It was observed [...] Read more.

In this paper, we report on achieving the hybridization effect in a Mie-based dielectric metamolecule and provide its physically intuitive picture. Hybridization results in the splitting of the initial overlapping resonance dips, thus leading to two new collective resonance modes. It was observed via the simulated displacement field distribution that the two modes behave as the in-phase and out-of-phase oscillation of two meta-atoms, thus enhancing and suppressing the intensity of the electric field at the gap between two meta-atoms. Moreover, since the two hybridized modes are caused by the interaction effect, the intensities of the electric field can be adjusted by several external factors, like applied forces and temperature. Taking advantage of this easy-equipped dielectric meta-device, certain zones in it can be applied to receive amplified signals and shielded noises of different frequencies in microwave communication fields. Moreover, due to the function of enhancing electric field intensities, it is also promising in wireless charging technology. Full article

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7 pages, 623 KiB

Open AccessArticle

Dual Aptamer-Functionalized 3D Plasmonic Metamolecule for Thrombin Sensing

by Timon Funck, Tim Liedl and Wooli Bae

Appl. Sci. 2019, 9(15), 3006; https://doi.org/10.3390/app9153006 - 26 Jul 2019

Cited by 29 | Viewed by 4503

Abstract

DNA nanotechnology offers the possibility to rationally design structures with emergent properties by precisely controlling their geometry and functionality. Here, we demonstrate a DNA-based plasmonic metamolecule that is capable of sensing human thrombin proteins. The chiral reconfigurability of a DNA origami structure carrying [...] Read more.

DNA nanotechnology offers the possibility to rationally design structures with emergent properties by precisely controlling their geometry and functionality. Here, we demonstrate a DNA-based plasmonic metamolecule that is capable of sensing human thrombin proteins. The chiral reconfigurability of a DNA origami structure carrying two gold nanorods was used to provide optical read-out of thrombin binding through changes in the displayed plasmonic circular dichroism. In our experiments, each arm of the structure was modified with one of two different thrombin-binding aptamers—thrombin-binding aptamer (TBA) and HD22—in such a way that a thrombin molecule could be sandwiched by the aptamers to lock the metamolecule in a state of defined chirality. Our structure exhibited a K_d of 1.4 nM, which was an order of magnitude lower than those of the individual aptamers. The increased sensitivity arose from the avidity gained by the cooperative binding of the two aptamers, which was also reflected by a Hill coefficient of 1.3 ± 0.3. As we further exploited the strong plasmonic circular dichroism (CD) signals of the metamolecule, our method allowed one-step, high sensitivity optical detection of human thrombin proteins in solution. Full article

(This article belongs to the Special Issue Nanomaterials for Sensing and Imaging Applications)

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8 pages, 3761 KiB

Open AccessArticle

Asymmetric Transmission in a Mie-Based Dielectric Metamaterial with Fano Resonance

by Xiaobo Wang, Haohua Li and Ji Zhou

Materials 2019, 12(7), 1003; https://doi.org/10.3390/ma12071003 - 27 Mar 2019

Cited by 14 | Viewed by 4249

Abstract

Chiral metamaterials with asymmetric transmission can be applied as polarization-controlled devices. Here, a Mie-based dielectric metamaterial with a spacer exhibiting asymmetric transmission of linearly polarized waves at microwave frequencies was designed and demonstrated numerically. The unidirectional characteristic is attributed to the chirality of [...] Read more.

Chiral metamaterials with asymmetric transmission can be applied as polarization-controlled devices. Here, a Mie-based dielectric metamaterial with a spacer exhibiting asymmetric transmission of linearly polarized waves at microwave frequencies was designed and demonstrated numerically. The unidirectional characteristic is attributed to the chirality of the metamolecule and the mutual excitation of the Mie resonances. Field distributions are simulated to investigate the underlying physical mechanism. Fano-type resonances emerge near the Mie resonances of the constituents and come from the destructive interference inside the structure. The near-field coupling further contributes to the asymmetric transmission. The influences of the lattice constant and the spacer thickness on the asymmetric characteristics were also analyzed by parameter sweeps. The proposed Mie-based metamaterial is of a simple structure, and it has the potential for applications in dielectric metadevices, such as high-performance polarization rotators. Full article

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9 pages, 1635 KiB

Open AccessArticle

A Mechanical Sensor Using Hybridized Metamolecules

by Haohua Li, Xiaobo Wang, Tian Yang and Ji Zhou

Materials 2019, 12(3), 466; https://doi.org/10.3390/ma12030466 - 3 Feb 2019

Cited by 1 | Viewed by 2445

Abstract

Hybridized metamaterials with collective mode resonance are usually applied as sensors. In this paper, we make use of one Mie-based hybridized metamolecule comprising of dielectric meta-atoms and an elastic bonding layer in order to detect the distances and applied forces. The hybridization induced [...] Read more.

Hybridized metamaterials with collective mode resonance are usually applied as sensors. In this paper, we make use of one Mie-based hybridized metamolecule comprising of dielectric meta-atoms and an elastic bonding layer in order to detect the distances and applied forces. The hybridization induced splitting results in two new collective resonance modes, of which the red-shifted mode behaves as the in-phase oscillation of two meta-atoms. Owing to the synergy of the oscillation, the in-phase resonance appears as a deep dip with a relatively high Q-factor and figure of merit (FoM). By exerting an external force, namely by adjusting the thickness of the bonding layer, the coupling strength of the metamolecule is changed. As the coupling strength increases, the first collective mode dip red-shifts increasingly toward lower frequencies. By fitting the relationship of the distance–frequency shift and the force–frequency shift, the metamolecule can be used as a sensor to characterize tiny displacement and a relatively wide range of applied force in civil engineering and biological engineering. Full article

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14 pages, 5661 KiB

Open AccessArticle

Plate-Focusing Based on a Meta-Molecule of Dendritic Structure in the Visible Frequency

by Suna Cheng, Di An, Huan Chen and Xiaopeng Zhao

Molecules 2018, 23(6), 1323; https://doi.org/10.3390/molecules23061323 - 31 May 2018

Cited by 2 | Viewed by 3475

Abstract

To study the potential application of metasurfaces in lens technology, we propose a dendritic meta-molecule surface (also referred to as a dendritic metasurface) and realize the focusing effect in the visible spectrum through simulations and experiments. Using asymmetric dendritic structures, this metasurface can [...] Read more.

To study the potential application of metasurfaces in lens technology, we propose a dendritic meta-molecule surface (also referred to as a dendritic metasurface) and realize the focusing effect in the visible spectrum through simulations and experiments. Using asymmetric dendritic structures, this metasurface can achieve distinct broadband anomalous reflection and refraction. When the metasurface is rotated by 180° around the z axis, anomalous reflection and refraction in vertically incident optical waves are in opposite directions. Considering this feature, a metasurface is designed to achieve a prominent plate-focusing effect. Samples with a transmission peak of green light at 555 nm, yellow light at 580 nm, and red light at 650 nm were prepared using bottom-up electrochemical deposition, and the focus intensity of approximately 10% and focal length of almost 600 µm were experimentally demonstrated. Full article

(This article belongs to the Special Issue Metallic Nanoparticles: From Synthesis, Structure-Property Relationships to Applications)

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