Spatially Arranged Unevenly Coupled Complementary Split Ring Resonators Loaded Highly Sensitive Microwave Sensor for Bio‐Fluids

ABSTRACT This study presents a sophisticated sensor based on microwave resonators employing complementary split ring resonators (CSRRs), engineered with uneven coupling and a unique spatial configuration to attain high sensitivity in the detection and characterization of bio‐fluids. The suggested sensor focuses on medical diagnostic applications, such as blood glucose monitoring and evaluation of electrolyte balance. The core, unevenly coupled CSRR‐loaded resonator sensor is developed using CST Microwave Studio (CST‐MWS), with its principal parameters refined to improve sensitivity at the target frequency of X‐band, roughly 9.51 GHz. Thereafter, the proposed sensor is constructed on a commercially available FR‐4 substrate, and its scattering parameters are assessed using a network analyzer to ascertain the resonance frequency and insertion loss of the unloaded structure. It exhibits a remarkable sensitivity of 409 MHz/ across a permittivity range of 2–10 while requiring only a minimal sample volume for testing. Experimental validation confirms the sensor's efficacy in detecting permittivity fluctuations in response to frequency shifts. The results validate that the sensor is very appropriate for glucose monitoring, dehydration detection, and identifying electrolyte imbalances in clinical and point‐of‐care applications. The proposed sensor attains a sensitivity of 4.405%, surpassing numerous previously reported designs.