ELC Coupled Hexagonal CSRR Sensor for Detection of Permittivity and Concentration

In this work, a highly sensitive microwave sensor for measuring the dielectric constant of liquid samples and concentration detection of aqueous solutions is proposed. The sensor is based on a hexagonal complementary split ring resonator loaded with an electric-LC electrode. The sensor adapts a web like structure so as to further improve the field confinement in a definite sensing region. The sensor has been modelled to resonate at 2.4 GHz of the ISM band with an overall substrate dimension of 20×16×1.53 mm3. A specimen holder made out of acrylonitrile-butadiene-styrene (ABS) plastic holder is employed in the region of maximum electric field strength of the sensor to inject different samples under test. The sensitivity and normalized sensitivity of the sensor are found to be 69.855 MHz/ɛ and 3.077%, respectively, which outperform many of the recently proposed sensors. Fitting technique has been employed to develop relations between complex permittivity/concentration of samples and the scattering parameters of the sensor. The results highlight the potential of ELC coupled HCSRR sensor in both dielectric characterization and ethanol concentration detection. The sensor has found to have the characteristics of high sensitivity, high resolution, and high measurement accuracy, which confirms its promising application in various fields.