Thermally invisible sensors

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.