High-Sensitivity Contactless Microwave Sensor Based on Rectangular Complementary Split Ring Resonator for Glucose Concentration Characterization

This paper presents a glucose concentration characterization sensor using a tri-rectangular complementary split ring resonator (TR -CRR) structure which used a binary mixed liquid between water and glucose as a liquid under test (LUT) to demonstrate the performance of the proposed sensor, in term of the measurement and detection. The LUTwas injected into glass capillary tube and inserted to alignment hold at the center of the TR-CRR structure. The proposed sensor was compared with two conventional sensors namely a single-rectangular complementary split ring resonator (SR-CSRR) and a double-rectangular CSRR (DR-CSRR). All the sensors were designed and fabricated on 0.8 mm thick FR4 substrate with total dimensions of 15 x 15 mm
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and operated at 2.50 GHz under unloaded LUT condition. All the sensors were measured with different concentrations of LUT for finding the sensitivity by compared the shifted resonance frequency in transmission coefficient. The results showed that the sensitivity of the TR-CRRproposed sensor was around 3 times and 2 times higher than SR-CSRR and DR-CSRR, respectively.