Highly-Sensitive Glucose Concentration Sensor Exploiting Inter-resonators Couplings

A microwave sensor for glucose concentration tracking in microliter-volume water-glucose solutions is presented. Novelty of this work relies in the use of couplings between two resonators to track liquid properties, which allows great sensitivities. The circuit is composed of two electrically coupled open-loop microstrip resonators. A low-permittivity dielectric sample holder is placed in the coupling region between the resonators, thus the coupling is affected by the dielectric properties of the solutions filling the sample holder. The electrical response of the device is dependent on this coupling, and thus on the properties of the solutions. Variations of the dielectric permittivity of the solutions due to the changes in the glucose concentrations can be tracked by the changes in the electrical response of the sensor. Measurements have been made to assess its behavior and performance. The obtained results are consistent with the existing literature and provide a remarkable enhancement from the previous work in terms of sensitivity.