Development and experimental evaluation of single-port substrate integrated waveguide resonator with dual-parameter sensitivity for non-invasive blood glucose monitoring

• Innovative sensor design: The study introduces a compact, non-invasive blood glucose sensor that uses a single-port substrate integrated waveguide (SIW) resonator with an X-shape topology. This specific X-shape is engineered to enhance electromagnetic field localization and interaction with biological tissue. • Dual-parameter sensing: Unlike many traditional designs, this sensor employs a dual-parameter strategy, tracking both reflection coefficient center (Hz) and level (dB) to detect glucose-induced variations in tissue permittivity. • High sensitivity and full clinical range: The sensor demonstrated a 100% “coverage efficiency,” successfully detecting glucose levels across the entire physiological range of 20–200 mg/dL. It achieved high sensitivity metrics up to 0.310 MHz/(mg/dL) in frequency and 0.333 dB/(mg/dL) in return loss during experimental trials. • In vivo validation: The device’s performance was validated through practical testing with five human volunteers under both fasting and post-glucose intake conditions. • Practical advantages: The sensor is fabricated on a low-loss, biocompatible Rogers substrate and operates at 1.7 GHz. Its single-port structure simplifies measurement by requiring only reflection data, making it a strong candidate for future portable or wearable monitoring systems. • Identified challenges: The study notes that inter-subject variability in tissue properties and the need for precise finger placement remain challenges. These findings emphasize the necessity for personalized calibration in future real-world applications. Current Blood Glucose (BG) monitoring techniques are invasive or semi-invasive and can impose financial and practical burden on patients. In this study a compact, non-invasive and single port Substrate Integrated Waveguide (SIW) loaded with X-shape has been present. The sensor resonant at 1.7 GHz, a dual parameter employed to evaluate the sensor by tracking the shift of resonance frequency in (MHz) and the reflection coefficient (dB) to detect glucose-induced changes in tissue permittivity. The device is designed using full-wave electromagnetic simulations with multilayer tissue models and validated experimentally on five human volunteers under controlled fasting and post-glucose conditions. Across the physiological range of 20 to 200 mg/dL, the sensor exhibits sensitivities up to 0.310 MHz per mg/dL and 0.333 dB per mg/dL, demonstrating consistent responsiveness to glucose variations. The results indicate that the proposed resonator can track glucose-related dielectric changes using a simple contact-based configuration. However, the measurements are influenced by subject-specific variability and sensor placement conditions, which currently limit generalization and repeatability. Further work is required to improve robustness, calibration, and validation on larger cohorts before practical deployment.