Measurement of thermal conductivity using the 3-omega method

A multitude of techniques currently exist for measuring the thermal conductivity of solid, liquid or gaseous materials. They fall into two main groups: stationary (steady-state) and transient (frequency or time) methods.

Among these methods, the 3-omega method, which is a transient method, can be applied to solids of various dimensions (solid, thin film or nanowire), liquids and gases. It can also be used to characterize soft tissues, revealing a little more of its potential. The main limitation of this technique lies in the preparation of the sensors associated with the different types of samples and the thermal models associated with them. The sensor used consists of a micrometrically wide resistor, in contact with the sample to be characterized, which enables small temperature variations to be measured. In the case of solid materials, this sensor is generally deposited directly onto the material to be characterized, using photolithography techniques. It can also be used as an external sensor (or as a free-standing sensor) for solid, liquid or gaseous samples.

This article situates the 3-omega method in relation to the various existing techniques for characterizing thermal conductivity. The theory associated with this method and the methodology to be followed to characterize the different sample shapes will be discussed, as will the estimation of errors associated with thermal models, sample geometry and physical properties.