Guiding conductive heat flux through thermal metamaterials

Vemuri, Krishna P.; Canbazoglu, F. M.; Bandaru, Prabhakar R.

doi:10.1063/1.4901885

Cited by 89 publications

(63 citation statements)

References 28 publications

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“…It is then the aim of this paper (which reviews many recent results and incorporates an overview of recent publications [22][23][24][25][26][27][28][29] from our group) to indicate that significant insight and control into the directionality of heat transport may still be exerted through considering the geometric characteristics of thermal conductivity. We show utilizing fundamental tenets, such as (a) that the net thermal conductivity of a composite can be altered through the arrangement of isotropic materials, and (b) the adaptation of the Fermat principle of least time, whereby heat flux choses the path of least resistance, may yield novel arrangements through which control over conductive heat flux may be achieved.…”

Section: 17mentioning

confidence: 99%

Layered thermal metamaterials for the directing and harvesting of conductive heat

et al. 2015

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The utility of a metamaterial, assembled from two layers of nominally isotropic materials, for thermal energy re-orientation and harvesting is examined. A study of the underlying phenomena related to heat flux manipulation, exploiting the anisotropy of the thermal conductivity tensor, is a focus. The notion of the assembled metamaterial as an effective thermal medium forms the basis for many of these investigations and will be probed. An overarching aim is to implement in such thermal metamaterials, functionalities well known from light optics, such as reflection and refraction, which in turn may yield insights on efficient thermal lensing. Consequently, the harness and dissipation of heat, which are for example, of much importance in energy conservation and improving electrical device performance, may be accomplished. The possibilities of energy harvesting, through exploiting anisotropic thermopower in the metamaterials is also examined. The review concludes with a brief survey of the outstanding issues and insights needed for further progress.

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Section: 17mentioning

confidence: 99%

Layered thermal metamaterials for the directing and harvesting of conductive heat

et al. 2015

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“…[ 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.…”

Section: Doi: 101002/adma201502513mentioning

confidence: 99%

“…[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.…”

mentioning

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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“…Hence, three transformed schemes with rotation angles of 30 • , 45 • , and 60 • were respectively created. As [37][38][39][40][41] pointed out, for all transformed schemes, larger anisotropy led to larger heat flux bending in the tunable cells. Hence, the thicknesses of PDMS and copper layers were made uniform, i.e., l A = l B = 0.0015 mm, in order to obtain the largest anisotropy in thermal conductivities based on Equation (12).…”

Section: Description Of Tunable Cell Schemementioning

confidence: 99%

“…Additionally, based on the effective medium theory [11], two kinds of thermal materials with large differences in conductivities are alternately combined to create a field of conductivity gradients. Once the selected materials are combined in parallel and in series under corresponding rotations, the heat flux bends [37][38][39][40][41] following the pre-designed direction. That means that the degree of rotation of the entire system and related material properties directly affect heat flux bending.…”

Section: Description Of Tunable Cell Schemementioning

confidence: 99%

Investigating the Thermodynamic Performances of TO-Based Metamaterial Tunable Cells with an Entropy Generation Approach

Zhang

et al. 2017

Entropy

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Active control of heat flux can be realized with transformation optics (TO) thermal metamaterials. Recently, a new class of metamaterial tunable cells has been proposed, aiming to significantly reduce the difficulty of fabrication and to flexibly switch functions by employing several cells assembled on related positions following the TO design. However, owing to the integration and rotation of materials in tunable cells, they might lead to extra thermal losses as compared with the previous continuum design. This paper focuses on investigating the thermodynamic properties of tunable cells under related design parameters. The universal expression for the local entropy generation rate in such metamaterial systems is obtained considering the influence of rotation. A series of contrast schemes are established to describe the thermodynamic process and thermal energy distributions from the viewpoint of entropy analysis. Moreover, effects of design parameters on thermal dissipations and system irreversibility are investigated. In conclusion, more thermal dissipations and stronger thermodynamic processes occur in a system with larger conductivity ratios and rotation angles. This paper presents a detailed description of the thermodynamic properties of metamaterial tunable cells and provides reference for selecting appropriate design parameters on related positions to fabricate more efficient and energy-economical switchable TO devices.

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Guiding conductive heat flux through thermal metamaterials

Cited by 89 publications

References 28 publications

Layered thermal metamaterials for the directing and harvesting of conductive heat

Layered thermal metamaterials for the directing and harvesting of conductive heat

Invisible Sensors: Simultaneous Sensing and Camouflaging in Multiphysical Fields

Investigating the Thermodynamic Performances of TO-Based Metamaterial Tunable Cells with an Entropy Generation Approach

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