3D-printed sensor design based on metamaterial absorber for characterization of solid and liquid materials

In this paper, a novel metamaterial absorber-based sensor design in the S-band region is proposed for the characterization of solid and liquid samples. Unlike typical microwave sensor structures, where the sensing and resonator layers are manufactured separately, the proposed sensor design has a monolithic structure with a cavity in the dielectric substrate on which the samples can be placed. Thanks to this structure, which can be easily manufactured precisely with 3D printing technology, both solid and liquid sample tests can be performed without the need for additional processing. The absorber of the proposed sensor design consists of an electricfield-coupled (ELC) resonator placed on the cavity-loaded substrate with the other side fully grounded. To ensure a strong interaction between the ELC resonator and sample materials, the resonator is aligned just on the cavity. In the design process, the absorption behavior of the monolithic structure depending upon the ELC resonator and dielectric environment was predicted with an equivalent analytical model. Moreover, many parametric analyses were carried out to achieve high absorbency and sensitivity properties. To validate the numerical design, a fabricated prototype was measured using two solid and three liquid samples. According to the simulation and measurement results, the proposed design with novel configuration exhibits high sensitivity performance compared with recently reported microwave sensor designs.