Thermally invisible sensors

¹ Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University - Shanghai 200438, China
² Department of Radiology, Changhai Hospital, Naval Medical University - Shanghai 200433, China
³ Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences - Shanghai 201800, China

^(a) 13307110076@fudan.edu.cn
^(b) jphuang@fudan.edu.cn

Received: 19 July 2020
Accepted: 7 September 2020

Abstract

Accurate temperature detection requires a thermal sensor with high performance. In general, once a thermal sensor is placed in a temperature field, it will distort the temperature field more or less. Therefore, the thermal sensor is inaccurate and thermally visible, which constitutes an issue in many practical applications. Here we propose a bilayer scheme to maintain the original temperatures in both sensor and matrix, yielding an accurate and thermally invisible sensor. By solving the linear Laplace equation (with temperature-independent thermal conductivity), we derive two groups of thermal conductivities to realize thermally invisible sensors, even considering geometrically anisotropic cases. These results can be directly extended to thermally nonlinear cases (with temperature-dependent thermal conductivity), as long as the ratio between the nonlinear thermal conductivities of sensor and matrix is a temperature-independent constant. These explorations are beneficial to temperature detection and provide insights into thermal camouflage.