High-Sensitivity Low-Cost 2.61 GHz DGS Sensor for Non-Invasive Glucose Level Monitoring

This work presents a loop-shaped (hairpin) resonator incorporating a defective ground structure (DGS) to enhance sensitivity for monitoring water-glucose solutions. The proposed sensor exhibits two resonant frequencies at 2.61 GHz and 4.07 GHz, with reflection coefficients of -46.60 dB and -23.00 dB, respectively. A set of measurements was conducted to compare the performance of the resonator with and without the DGS under two sample-placement configurations: one with water and water-glucose solutions positioned over the feed lines and metallic resonant elements, and another with the water-glucose solutions placed directly over the ground plane. Among the evaluated cases, the ground-plane configuration proved to be the most advantageous, as it produced no frequency shift while yielding distinct magnitude responses of -41.91 dB, -45.62 dB, -47.74 dB, and -49.69 dB for glucose concentrations of 100, 150, 200, and 250 mg/dL, respectively. Overall, the resonator with the defective ground structure consistently demonstrated higher sensitivity and a more stable response pattern, indicating its strong potential for glucose-level monitoring applications.