Anomalous refraction of heat flux in thermal metamaterials

Vemuri, Krishna P.; Bandaru, Prabhakar R.

doi:10.1063/1.4867027

Cited by 49 publications

(29 citation statements)

References 13 publications

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“…Such detailed formulations also illuminate the possibility of negative refraction, 23 as will be considered in the next section, where the transmitted heat flux could bend anomalously with respect to the interface normal.…”

Section: E Experimental Demonstrationsmentioning

confidence: 99%

“…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%

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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: E Experimental Demonstrationsmentioning

confidence: 99%

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.…”

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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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“…[4][5][6][7][8][9] When such µ-ILEDs are integrated with the biological tissue, the heat dissipation in the substrate is uniform in all directions and the maximum temperature increase in the tissue is located at the substrate/tissue interface. The recent work on thermal metamaterials, [10][11][12] consisting of layered metal and polymer materials, shows that the heat flow can be guided to yield orthotropic thermal conductivities along in-plane and off-plane directions. This orthotropic feature provides a novel route to further reduce the adverse thermal response of µ-ILEDs by controlling the heat dissipation along the in-plane directions much more than that along the off-plane direction (to the tissue).…”

confidence: 99%

Analytical investigations on the thermal properties of microscale inorganic light-emitting diodes on an orthotropic substrate

Chen

Xing

et al. 2017

AIP Advances

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The microscale inorganic light-emitting diodes (μ-ILEDs) create novel opportunities in biointegrated applications such as wound healing acceleration and optogenetics. Analytical expressions, validated by finite element analysis, are obtained for the temperature increase of a rectangular μ-ILED device on an orthotropic substrate, which could offer an appealing advantage in controlling the heat flow direction to achieve the goal in thermal management. The influences of various parameters (e.g., thermal conductivities of orthotropic substrate, loading parameters) on the temperature increase of the μ-ILED are investigated based on the obtained closed-form solutions. These results provide a novel route to control the temperature distribution in the μ-ILED system and provide easily interpretable guidelines to minimize the adverse thermal effects.

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Anomalous refraction of heat flux in thermal metamaterials

Cited by 49 publications

References 13 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

Analytical investigations on the thermal properties of microscale inorganic light-emitting diodes on an orthotropic substrate

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