Non Invasive Glucose Detection Using Multiple Cell Triangular CSRR Sensor

This research proposes a novel microwave sensor, the Multiple Cell Triangular Complementary Split-Ring Resonator (MC- TCSRR), designed for non-invasive glucose level monitoring. The MC-TCSRR is a metamaterial structure adept at covering a spectrum of glucose concentrations, from low (50 mg/dL) to high (200 mg/dL). It is built on an FR4 substrate, and is excited by a 50-ohm microstrip line etched on the underside. Placing two fingers over the sensing area induces changes in the input impedance, resulting in a shift in the resonance frequency. These impedance variations are closely tied to changes in blood permittivity, which fluctuate with different glucose levels. In simulations, the Cole-Cole model is employed to simulate the blood at various glucose concentrations, and the sensor exhibits a maximum sensitivity of 7.1 × 10–<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> dB/(mg/dL) and 400 kHz/(mg/dL). In vitro tests using deionized aqueous glucose solutions (50–200 mg/dL) demonstrated leftward shifts in the resonant frequency of the transmission response. The fabricated MC-TCSRR prototype exhibited a maximum sensitivity of 429 kHz/(mg/dL).