A Negative Conductivity Material Makes a dc Invisibility Cloak Hide an Object at a Distance

Yang, Fan; Mei, Zhong Lei; Yang, Xuan; Jin, Tian Yu; Cui, Tie Jun

doi:10.1002/adfm.201300226

Cited by 46 publications

(47 citation statements)

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“…Soon after, an ultrathin dc electric cloak [21] and a dc electric concentrator [22] are reported using similar resistor networks. More recently, an exterior dc cloak [23] and an active dc cloak [24] have been experimentally realized by the use of inhomogeneous and anisotropic conductivities with the aid of active sources. It is noted that EM invisibility cloaks made of L-C networks have been experimentally demonstrated [25] .…”

Section: Introductionmentioning

confidence: 99%

“…Besides making objects invisible [1][2][3][4] , many other novel devices are rapidly emerging, with a representative one being a concentrator [5,6] that can enhance the energy density of incident waves in a given area. In addition to manipulation of EM waves [1][2][3][4][5][6] , the theoretical tool of coordinate transformation has been extended to other areas of physics (such as acoustic waves [7] , matter waves [8] and elastic waves [9] ).Recently, many significant achievements have been made in the manipulation of magnetostatic field [10][11][12][13][14][15] , thermal conduction [16][17][18][19] , and electrostatic field [20][21][22][23][24] . In 2007, Wood and Pendry proposed a dc metamaterial that pointed the way towards the design of static magnetic cloak [10] , and the dc metamaterial was experimentally verified soon afterwards [11] .…”

mentioning

confidence: 99%

“…Recently, many significant achievements have been made in the manipulation of magnetostatic field [10][11][12][13][14][15] , thermal conduction [16][17][18][19] , and electrostatic field [20][21][22][23][24] . In 2007, Wood and Pendry proposed a dc metamaterial that pointed the way towards the design of static magnetic cloak [10] , and the dc metamaterial was experimentally verified soon afterwards [11] .…”

mentioning

confidence: 99%

“…Our design schemes do not rely on transformation optics, and we can thus avoid the problems present in previous proposals (such as inhomogeneous and anisotropic parameters that need to mimicked via complicated resistor networks [20][21][22][23][24] ). Also, the proposed schemes, derived directly from the electric conduction equation, are exact rather than approximate ones.…”

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confidence: 99%

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Manipulating DC Currents with Bilayer Bulk Natural Materials

Han

Luo

et al. 2014

Advanced Materials

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Abstract:The principle of transformation optics has been applied to various wave phenomena (e.g., optics, electromagnetics, acoustics and thermodynamics). Recently, metamaterial devices manipulating dc currents have received increasing attention which usually adopted the analogue of transformation optics using complicated resistor networks to mimic the inhomogeneous and anisotropic conductivities. We propose a distinct and general principle of manipulating dc currents by directly solving electric conduction equations, which only needs to utilize two layers of bulk natural materials. We experimentally demonstrate dc bilayer cloak and fan-shaped concentrator, derived from the generalized account for cloaking sensor. The proposed schemes have been validated as exact devices and this opens a facile way towards complete spatial control of dc currents. The proposed schemes may have vast potentials in various applications not only in dc, but also in other fields of manipulating magnetic field, thermal heat, elastic mechanics, and matter waves.Controlling electromagnetic (EM) fields so as to render an object invisible, has been a long-standing dream for many researchers over the decades [1,2] . On the basis of the invariance of Maxwell's equations where equivalence is established between metric transformations and changes in material parameters, transformation optics [3] and conformal mapping [4] have been 2 developed to manipulate EM wave propagation in a practically arbitrary manner. Besides making objects invisible [1][2][3][4] , many other novel devices are rapidly emerging, with a representative one being a concentrator [5,6] that can enhance the energy density of incident waves in a given area. In addition to manipulation of EM waves [1][2][3][4][5][6] , the theoretical tool of coordinate transformation has been extended to other areas of physics (such as acoustic waves [7] , matter waves [8] and elastic waves [9] ).Recently, many significant achievements have been made in the manipulation of magnetostatic field [10][11][12][13][14][15] , thermal conduction [16][17][18][19] , and electrostatic field [20][21][22][23][24] . In 2007, Wood and Pendry proposed a dc metamaterial that pointed the way towards the design of static magnetic cloak [10] , and the dc metamaterial was experimentally verified soon afterwards [11] . Recently, the dc magnetic cloak is theoretically investigated [12] and experimentally realized using superconductors and ferromagnetic materials [13,14] . By using the same materials as dc magnetic cloak, the theoretical realization of a dc magnetic concentrator is also demonstrated [15] . On the basis of form invariance of the heat conduction equation, transformation thermodynamics is investigated to manipulate diffusive heat flow [16] ; through tailoring inhomogeneity and anisotropy of conductivities, transient thermal cloaking has been experimentally demonstrated [17] . In addition, manipulation of heat flux with only two kinds of materials (by utilizing a multilayered composite approach) has been ...

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Manipulating DC Currents with Bilayer Bulk Natural Materials

Han

Luo

et al. 2014

Advanced Materials

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“…More recently, metamaterials were presented that control the DC current [18][19][20][21][22][23][24][25][26] and the heat fl ux. [27][28][29][30][31][32][33][34][35][36][37] However, these devices were designed to cloak an object in a single physical fi eld.…”

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confidence: 99%

Invisible Sensors: Simultaneous Sensing and Camouflaging in Multiphysical Fields

et al. 2015

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maintaining its receiving ability. However, this technique is only valid for a single physical fi eld, e.g., an invisible electromagnetic sensor or an invisible acoustic detector. [2][3][4] Consequently, a single-functional sensor is invisible to an acoustic monitoring receiver, but it can be easily detected using a remote thermal imager. Is it possible to create a sensor that is invisible in multiple physical fi elds while maintaining the same sensing functionality? This is very challenging, if not impossible, to achieve, even using the concept of metamaterials, which are man-made composites that control waves and energy fl ux in unprecedented ways, resulting in exotic behaviors that are absent in nature. For example, electromagnetic metamaterials were proposed to manipulate electromagnetic waves and produce an invisibility cloak. [5][6][7] This pioneering idea motivated a number of significant applications, such as the wave concentrator and rotator. [8][9][10] Other than the electromagnetic waves, metamaterials have been created to manipulate other waves such as acoustic waves, [11][12][13] elastic waves, [ 14,15 ] magnetostatic fi elds, [ 16 ] and static forces.[ 17 ]More recently, metamaterials were presented that control the DC current [18][19][20][21][22][23][24][25][26] and the heat fl ux. [27][28][29][30][31][32][33][34][35][36][37] However, these devices were designed to cloak an object in a single physical fi eld.Advanced and multifunctional metamaterials are highly desirable for most practical applications. More recently, some attempts to cloak an object in multiple physical fi elds have been made, in particular, the bifunctional thermalelectric invisibility cloak [ 38 ] and independent manipulation [ 39 ] were proposed. Later, the fi rst experiment was carried out to simultaneously cloak an air cavity in the electric and thermal fi elds. [ 40 ] This sample was fabricated through a sophisticated man-made metamaterial structure with many holes drilled in a silicon plate that were, then, fi lled with poly(dimethylsiloxane) (PDMS). In our work, we found that natural materials with simple structure can also simultaneously manipulate multiphysical fi elds. We fabricated a device that acted as a "mask" for both thermal and electric fi elds and behaved as a multifunctional invisible sensor.To date, the theory of "cloaking a sensor" is only valid for a single physical fi eld. [ 1 ] In this study, we present the fi rst invisible sensor theory for static multiphysical-fi eld. This multiphysical invisible sensor has three features that distinguish it from conventional DC and thermal metamaterial devices, especially different from the bifunctional cloak for an air cavity. [ 40 ] First, we allow the sensor to "see through and behind" the cloaked region in multiphysical fi elds. As a result, the sensor is invisible and receives proportional incoming signals at the same time, and it is able to "open its eyes" behind the cloak to receive information from the outside multiphysical When a sensor is used to probe a ph...

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Restoring Intrinsic Properties of Electromagnetic Radiators Using Ultralightweight Integrated Metasurface Cloaks

Jiang

Sieber

Kang

et al. 2015

Adv Funct Materials

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The concept of invisibility has garnered long‐standing interest throughout human history but has only been realized experimentally within the past decade, albeit over a limited bandwidth. While the physical wave phenomenon of a reduced scattering signature has been demonstrated with different cloaking methods such as transformation optics and scattering cancellation, such technology has yet to be incorporated into any practical real‐world devices. Through the use of quasi‐2D functional metasurfaces, the long‐standing issue of simultaneous mutual coupling and radiation blockage is addressed that occurs when two or more electromagnetic radiators are placed in close proximity to one another. The proposed compact and ultralightweight metasurfaces, comprising arrays of subwavelength electric and magnetic resonators with tailored dispersive properties, are capable of fully restoring the intrinsic properties of real‐world electromagnetic radiators when placed in a multiradiator environment. This work introduces a general design approach to bridge the gap between the theory and practice for cloaks, which is applicable to microwave, terahertz, and optical radiators, as well as acoustic and thermal sources. Moreover, this technology provides an unprecedented opportunity for enabling high‐density deployment of radiating systems with low interference and undistorted signal wave fronts.

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A Negative Conductivity Material Makes a dc Invisibility Cloak Hide an Object at a Distance

Cited by 46 publications

References 30 publications

Manipulating DC Currents with Bilayer Bulk Natural Materials

Manipulating DC Currents with Bilayer Bulk Natural Materials

Invisible Sensors: Simultaneous Sensing and Camouflaging in Multiphysical Fields

Restoring Intrinsic Properties of Electromagnetic Radiators Using Ultralightweight Integrated Metasurface Cloaks

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