Transforming heat transfer with thermal metamaterials and devices

Abstract

The demand for sophisticated tools and approaches in heat management and control has triggered fast development of emerging fields including conductive thermal metamaterials, nanophononics, far-field and near-field radiative thermal management, etc. In this review, we cast a unified perspective on the control of heat transfer, based on which the related studies can be considered as complementary paradigms toward manipulating physical parameters and realizing unprecedented phenomena in heat transfer using artificial structures, such as thermal conductivity in heat conduction, thermal emissivity in radiation, and properties related to multi-physical effects. The review is divided into three parts that focus on the three main categories of heat flow control, respectively. Thermal conduction and radiation are emphasized in the first and second parts at both macro-and micro-scale. The third part discusses the efforts to actively introduce heat sources or tune the material parameters with multi-physical effects in both conduction and radiation, including works using thermal convection. We conclude the review with challenges in this research topic and new possibilities about topological thermal effects, heat waves, and quantum thermal effects.

Robustly printable freeform thermal metamaterials

“…As a diffusive counterpart, thermal metamaterials have exhibited great potentials on manipulating, controlling, and processing the heat flow, and enabled many promising thermal metadevices, including thermal cloak 14 – 17 , concentrator 16 , 18 , rotator 18 , 19 , camouflage 20 – 22 , and illusion 20 , 23 , etc. However, three long-standing challenges remain formidable for state-of-the-art thermal metamaterials 13 , 24 – 27 . Firstly, the transformation optics method results in thermal metamaterials with inhomogeneous and anisotropic material parameters that are hard to realize by naturally existing materials.…”

Diffusive skin effect and topological heat funneling

“…In diffusive systems that are non-Hermitian inherently, the thermal metamaterials advanced rapidly as it enables various agile and flexible manipulation of heat flow 27,28 . Based on the theory of transformation thermotics, fruitful progresses have been achieved, such as thermal cloaks that conceal objects in heat conduction or radiative camouflages against infrared detection [29][30][31] , thermal diodes and concentrators that isolate and harvest heat directionally [32][33][34][35] .…”

Non-Hermitian Electromagnetic Metasurfaces at Exceptional Points (Invited Review)

“…Further evaluation will be needed to verify their uses in practical applications ranging from biomedical sensing to optical imaging [118]. Our perspective of non-Hermitian metasurfaces from basic science to potential applications could also provoke the research of metamaterials in other regimes including acoustics, mechanics, and thermotics [119,120].…”