Design and Validation of Substrate Integrated Waveguide-Based Blood Glucose Measurement Sensor

The increasing global prevalence of diabetes necessitates the development of accurate, reliable, and miniaturised glucose sensing technologies. Microwave-based sensors offer a promising alternative to conventional electrochemical methods due to their less invasive nature and real-time monitoring capabilities. However, previous microwave glucose sensors have often lacked comprehensive validation, limiting their practical usability. Many existing studies rely on simplified simulations without detailed parametric studies or fail to establish a strong correlation between theoretical models and experimental results, resulting in discrepancies in sensor performance. This study introduces a Cross-Slot Substrate Integrated Waveguide (CSSIW) sensor that overcomes these limitations by implementing a rigorous multi-level validation approach, including analytical modeling, full-wave electromagnetic simulations, and experimental verification. The sensor’s X-slot structure enhances electric field concentration, significantly improving sensitivity while maintaining a compact form factor (13×9 mm). Through eigenmode analysis and parametric studies, the sensor’s resonant frequency shift is optimised to detect glucose concentration variations with high precision. Experimental validation using glucose solutions at physiological concentrations (20–200 mg/dL) demonstrates a sensitivity of 0.563 MHz/(mg/dL), closely aligning with simulated results (0.415 MHz/(mg/dL)), confirming its accuracy and robustness. Compared to previous works, this study addresses prior shortcomings by providing a detailed investigation of field interactions, quality factor evaluation, and environmental dependencies, ensuring a comprehensive understanding of the CSSIW sensor’s performance. The findings confirm that the proposed sensor achieves low insertion loss (1.13 dB), strong impedance matching (-18.7 dB return loss), and full physiological range coverage, making it a promising candidate for next-generation glucose monitoring solutions.