The 3-Omega method is based on the principle of Joule heating and the resulting temperature oscillations in a material. A metal line, which acts as both a heater and thermometer, is deposited on the surface of the material under investigation. An alternating current (AC) at angular frequency ω is passed through the metal line, producing heat at a frequency of 2ω due to the Joule heating effect. The resulting temperature oscillations in the material lead to a voltage response at a frequency of 3ω, hence the name "3-Omega" method.
