The 3ω harmonic detection method has been widely applied to develop the thermal functional materials and for the fabrication of devices in fields such as aerospace and energy conservation. It is adaptable for measuring the thermal conductivity of materials with various geometries, ranging from macroscopic to micro- and nanoscale, in both in-plane and out-of-plane directions. This tutorial introduces the measurement principles of the 3ω method and highlights important considerations for its application to different materials.
Yang et al. (2025) studied this question.