Integrated System for High-Sensitivity Differential Microwave Glucose Sensing

This study introduced two devices for detecting the concentration of glucose in aqueous solutions. To enhance robustness and reduce tolerance, a differential method was employed. Initially, a basic sensor based on a defected ground structure (DGS) was designed. To optimize the performance of the microwave sensor, the squares of the DGS were optimized using an adaptive genetic algorithm (AGA). The performance enhancement was demonstrated through the difference in resonant frequencies and improved electric field distribution. The use of glass microcapillary tubes allowed for noninvasive sample handling. The sensitivity of the optimized device is more than 1.6 times that of the basic structure, reaching 5.63 MHz/mg
$\cdot $
mL−1. Also, the experiment showed that the frequency shift response of the sensor to a 3.6-mg/mL glucose solution remained almost unchanged in the temperature range of 20 °C–40 °C, which proved that the sensor can avoid the influence of temperature. Subsequently, an integrated system was developed to directly display the concentration results, providing consistent readings from the sensors. The system demonstrated a response time of within 2 s, indicating real-time detection capabilities for glucose sensing.