This paper presents a non-invasive and ultra-sensitive microwave biosensor for real-time glucose monitoring, operating in the 2.4 GHz ISM band. The proposed sensing platform employs a compact \(2 \times 2\) square-shaped pass-band metamaterial array as the primary sensing unit, while an integrated stop-band metamaterial layer is utilized as an electric-field shielding structure. This complementary metamaterial configuration enables strong field confinement within the sensing region, leading to a high quality factor and enhanced measurement stability. The sensing principle is based on the strong interaction between electromagnetic waves and the dielectric properties of biological media. Variations in glucose concentration modify the effective permittivity of the probed sample, which in turn produces measurable shifts in the resonance frequency of the metamaterial array. The \(2 \times 2\) pass-band metamaterial architecture is specifically designed to localize the electric field near the sensing interface, thereby improving sensitivity to subtle dielectric perturbations associated with glucose fluctuations. Numerical analyses performed using glucose–water mixtures and blood-mimicking fluids reveal clear and monotonic resonance shifts across physiologically relevant glucose levels. Experimental validation using a Vector Network Analyzer confirms consistent frequency shifts for glucose concentrations ranging from 70 to 120 mg/dL. Furthermore, a radar-based demonstrator was employed for both in-vitro and in-vivo fingertip measurements, yielding identifiable spectral signatures that reliably track changes in glucose concentration. With a compact footprint of \(60.4 \times 75 \times 1.6\) mm \(^{3}\) , low fabrication cost, and suitability for wearable integration, the proposed sensor represents a promising non-ionizing solution for continuous glucose monitoring in diabetes management.
