Development of Dual-Parametric CSRR-Based MPA Sensor for Non-Invasive Blood Glucose Monitoring

A complementary split ring resonator (CSRR)-based microstrip patch sensor is presented for noninvasive estimation of blood glucose concentration. The device employs a triangular patch with a CSRR etched in the ground plane to realize two ISM bands: 2.42–2.62 GHz for wireless telemetry and 5.17–5.24 GHz for sensing, where the structure operates as a microwave resonator. Geometry and feed parameters were optimized to sharpen the S-parameter response and improve glucose-dependent sensitivity. A multilayer human-thumb phantom was constructed, and blood glucose level was swept from 100 to 300 mg/dL to quantify frequency-selective detection while complying with safety constraints. Changes in glucose level alter the tissue permittivity in the resonator-finger configuration, resulting in measurable shifts in resonant frequency and S ₁₁ magnitude, which enables a dual-parameter readout. The prototype exhibits frequency sensitivity of 160 kHz/mg·dL⁻¹ and magnitude sensitivity of 0.0654 dB/mg·dL⁻¹. The sensor was fabricated using conventional PCB etching to validate the simulated design. The measured S-parameters closely follow simulations with minor deviations attributable to fabrication tolerances and tissue-model simplifications. Specific absorption rate (SAR) analysis yields 0.397 W/kg averaged over 1 g of tissue, within commonly accepted IEEE exposure limits. The compact, low-cost, dual-band architecture and dual-parameter sensing indicate strong potential for real-time, noninvasive glucose monitoring and future integration into wearable systems.