Permittivity and Concentration Measurements Based on Coplanar Waveguide and Split Ring Resonator Sensor

Traditional methods for dielectric characterization and concentration measurements are hindered by technical limitations, the requirement for sample pretreatment, and complex instrument operation. To address these issues, a sensor that combines coplanar waveguide (CPW) and split ring resonator (SRR) technology is proposed in this article, with the resonance frequency of 1.87 GHz and a corresponding transmission coefficient of up to -1.6 dB. This sensor enables nondestructive, real-time, and convenient measurements without the need for sample pretreatment. Organic solvents, including n-hexane, carbon tetrachloride, and ethyl acetate, are characterized based on CPW-SRR sensor. The resonance frequency shifts range from 1.4 to 12.2 MHz in the sensor when samples with relative permittivity ranging from 1.89 to 80.1 are measured. In addition, for the volume fractions (0%-100%) of ethanol solution and methanol-ethanol mixed solution, the sensor produces transmission coefficient responses of -1.625 to -1.468 and - 1.556 to -1.464 dB, respectively. The sensor offers advantages of low loss, compact size, and cost-effectiveness, making it a promising technical solution for applications in microwave sensors, chemistry analysis, and integrated circuits.