Planar microwave sensors are considered an attractive choice to noninvasively probe the dielectric attributes of biological tissues due to their low cost, simple fabrication, miniature scale, and minimum risk to human health. This paper develops and measures a novel microwave biosensor for non-invasive real-time monitoring of glucose level. The design comprises a rectangular plexiglass channel integrated on a triple-pole complementary split ring resonator (TP-CSRR). The proposed sensor operates in the centimeter-wave range 1–6 GHz and is manufactured using PCB on top of an FR4 dielectric substrate. The sensor elements are excited via a coupled microstrip transmission-line etched on the bottom side of the substrate. The integrated CSRR-based sensor is used as a near-field probe to non-invasively monitor the glucose level changes in the blood mimicking solutions of clinically relevant concentrations to Type-2 normal diabetes (70–120 mg/dL), by recording the frequency response of the harmonic reflection and transmission resonances. This indicates the sensor's capability of detecting small variations in the dielectric properties of the blood samples that are responsive to the electromagnetic fields. The proposed sensor is verified through practical measurements of the fabricated design. Experimental results obtained using a Vector Network Analyzer (VNA) demonstrate a sensitivity performance of about 6.2 dB/(mg/ml) for the developed triple-pole sensor that significantly outperforms the conventional single-pole and other proposed sensors in the literature in terms of the resonance amplitude resolution.

中文翻译：

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使用基于三极 CSRR 的新型微波生物传感器无创实时监测葡萄糖水平

平面微波传感器由于成本低、制造简单、规模小以及对人类健康的风险最小，被认为是一种有吸引力的选择，可以无创地探测生物组织的介电属性。本文开发并测量了一种用于无创实时监测血糖水平的新型微波生物传感器。该设计包括一个集成在三极互补裂环谐振器 (TP-CSRR) 上的矩形有机玻璃通道。拟议的传感器在 1-6 GHz 的厘米波范围内运行，并使用 FR4 介电基板顶部的 PCB 制造。传感器元件通过蚀刻在基板底部的耦合微带传输线激发。基于 CSRR 的集成传感器用作近场探头，通过记录与 2 型正常糖尿病临床相关浓度 (70–120 mg/dL) 的血液模拟溶液中的葡萄糖水平变化，无创地监测血糖水平变化。谐波反射和传输共振的频率响应。这表明传感器能够检测响应电磁场的血样介电特性的微小变化。通过对制造设计的实际测量来验证所提出的传感器。使用矢量网络分析仪 (VNA) 获得的实验结果表明灵敏度性能约为 6。