Chemical Liquid and Concentration Sensing Applications Based on an All-Dielectric Absorber

In this study, a novel all-dielectric absorber structure whose unit cell is composed of a cylindrical dielectric resonator (CDR), an inner cylindrical dielectric container (CDC), a sensing layer, an outer CDC, and a dielectric support substrate is proposed for microwave S-Band sensing applications. The sensing performance of the proposed structure is numerically analyzed in terms of the dielectric constant and loss tangent of the analyte material placed in the sensing layer. It is observed that the frequency of absorption peak, absorption peak level, and absorption bandwidth depend on the change in the dielectric constant and loss tangent of the analyte material. For further analysis, the electric and magnetic field distributions are investigated for different dielectric constants of the analyte, and their effects on the absorption spectra are discussed. The proposed absorber structure has been tested for two different CDRs (i.e., acetone and ethyl methyl ketone) in two physical sensing applications, which are chemical liquid sensing and concentration sensing of ethanol-deionized water solutions. The simulation and the experiment results are found to be in good agreement. The results show that the absorption peak frequency changes almost linearly with the change in the analyte dielectric constant over an extensive dielectric constant range, making the design a good candidate for possible sensor applications.