Adulteration Detection of Glycol in Medical Grade Solvents Using the CSRR Loaded Stepped Coplanar Waveguide

This study presents a novel CSRR-loaded stepped-CPW sensor to detect adulteration levels of glycol in medical-grade solvents. The proposed RF system comprising the stepped-CPW resonant sensor and specially designed molded glass capillary tube as a sample holder, is well suited for detecting small levels of adulteration in bio-grade glycerol. The main advantage of the proposed sensor is its strong field confinement in the sensing region, defined in terms of the shift in the resonance frequency resulting from changes in the dielectric constant. It is demonstrated that the two-ring CSRR topology, excited by the stepped-CPW and designed on a 0.8 mm thick FR-4 substrate operating at 8 GHz, provides improved sensitivity and high Q-factor compared to its single-ring counterpart. The proposed sensor is tested to detect the adulteration level of EG in medical glycerol. Various adulteration levels of EG in glycerol can be detected using the proposed device due to a substantial shift in the resonant frequency with even a small change in the adulteration level. This study introduces a comprehensive theoretical framework, including vital factors to be considered during the design phase, and explores the usage of the proposed sensor for quality monitoring of various types of medical-grade fluids.