Efficient approach for dielectric permittivity measurements of liquids adopting a 3D-printed cavity resonator

This paper presents an operator-friendly and cost-efficient approach to characterize the dielectric permittivity of liquids flowing in narrow tubes, such as drainage tubes used as part of the wound healing process in hospitals. The approach is based on an oscillator such that the characterization can be achieved with minimal operator (e.g., nurse) training. The oscillator's frequency is set by a 3D-printed cavity resonator as to offer flexibility for the tube line to pass through. The oscillator design had to be tailored to ensure the oscillation condition to be met over a wide range of varying liquid compositions passing through the 3D-printed cavity resonator. The design and results of a proof-of-concept implementation are presented and discussed.