Coupled-line sensor setup with liquids and solids permittivity sensing capability developed with the use of 3D printing technology

Abstract

A novel coupled-line sensor setup is introduced allowing for permittivity change monitoring and characterization of both liquid and solid dielectric materials. The four-port coupled-line sensor is proposed together with the 3D printed assembly. A via-shorted edge-coupled two-sided coupled line section is realized to ensure identical sensitivity on the material-under-test placed on both sides of the sensor. The advantage of such a construction is that solid calibration samples with well-defined properties can be used to calibrate the setup when either solid or, what is especially useful, liquid materials are to be measured. An exemplary setup was fabricated using laminate and FDM (Fused Deposition Modeling) type 3D printing technologies and utilized for measurement of various dielectric materials including liquids (butan-2-ol, ethanol, propan-1-ol and propan-2-ol) and solid samples (Arlon 25N and Arlon AD600 laminates). The obtained results prove the usefulness of the proposed setup for characterization of materials featuring frequency dependent complex permittivity.