The Hotdisk method or the Transient Plane Source Method as it is also called uses a plane double spiral sensor, a special mathematical model describing the heat conductivity and precise electronics, to measure Thermal Transport Properties. It covers a thermal conductivity range of 4-5 orders of magnitude and can be used for measuring various kinds of materials, such as solids, powders, liquids, pastes and thin films etc. The method was developed by Dr Silas Gustavsson at Chalmers University of technology, Sweden, and is sometimes referred to as ”the Gustavsson Probe”. The probe is a flat sensor with a continuous double spiral of electrically conducting nickel (Ni) metal etched out of thin foil and clad between two layers of Kapton. The thin Kapton provides electrical insulation and mechanical stability to the sensor. The sensor is placed between the surfaces of two sample pieces. During the measurement a current passes through the nickel and creates an increase in temperature. The heat generated dissipates through the sample on either side of the sensor at a rate depending on the thermal transport characteristics of the material. By recording temperature vs. time response in the sensor, the characteristics of the material can be calculated.