Active thermal metasurfaces for remote heating/cooling by mimicking negative thermal conductivity

TL;DR

This paper introduces a method to create active thermal metasurfaces that mimic negative thermal conductivity, enabling long-focus thermal lenses for remote heating and cooling, verified through experiments.

Contribution

The study proposes a novel approach to realize negative thermal conductivity using active metasurfaces, enabling long focal length thermal lenses for remote temperature control.

Findings

Successfully designed a thermal lens with a focal length of 19.8mm

Demonstrated remote heating/cooling using the thermal lens

Expanded the scope of thermal conductivity manipulation

Abstract

Remote temperature control can be obtained by a long-focus thermal lens that can focus heat fluxes into a spot far away from the back surface of the lens and create a virtual thermal source/sink in the background material, around which the temperature field distribution can be remotely controlled by changing the parameters of the thermal lens. However, due to the lack of negative thermal conductivity, the existing thermal lenses have extremely short focal lengths and cannot be used to remotely control the temperature field around the virtual thermal source/sink. In this study, we theoretically propose a general approach to equivalently realize negative thermal conductivity by elaborately distributed active thermal metasurface (ATMS), then use the proposed ATMS to implement a novel thermal lens with long focal length designed by transformation thermodynamics, and experimentally verify the performance of the designed long-focus thermal lens with measured focal length f=19.8mm for remote heating/cooling. The proposed method expands the scope of the thermal conductivity and open up new ways to realize unprecedented thermal effects with effective negative thermal conductivity, such as "thermal surface plasmon polaritons", thermal superlens, thermal tunneling effect, and thermal invisible gateway.