The tuning fork principle is used to measure density and viscosity, for example when assessing the aging of battery coolants in BEVs.
TFS is based on the tuning fork principle. The natural frequency of a tuning fork depends on the density of the medium surrounding it. The time in which the natural oscillation decays (damping) is a measure of the medium’s viscosity. In the TFS process, the tuning fork is magnetically excited. This means that the tuning fork is first excited to a forced oscillation and then continues to oscillate at its natural frequency. During this stage, microcontroller-based electronics determine both the natural frequency and the damping factor of the decaying oscillation. These two values can then be used to directly infer the density and viscosity of the medium.