Frequency selective metasurface based radio frequency glucose sensor with a periodic array of meta cells

Nowadays, the operating principle of most of the experimental electromagnetic glucose sensors is based on the effect of an anomalous dispersion caused by a direct contact between an object under test and a two-dimensional metasurface. Due to the repeated uses, the metasurface will be subjected to a chemical attack over time. To avoid this problem, this work proposes a novel glucose sensor that is equipped with an interfacial dielectric layer of 0.254 mm thickness to separate the object under test and the metasurface. The results of our analysis suggest that, if the interfacial dielectric layer is sufficiently thin, there will be no shortage of sensitivity in the proposed sensor. Consistent with our theoretical prediction, the proposed sensor was found to resonate at 9-10 GHz, with its resonant frequency responding to the glucose concentration in a dose dependent manner. The correlation the resonant frequency shift and the glucose concentration was found to be highly linear over the clinical diabetic range with a sensitivity of 4 MHz/(mg dL^-1). However, we could not obtain the same or similar sensitivity when the interfacial layer was substituted with a similar dielectric layer of 1 mm thick. Overall, the presence of the interfacial dielectric layer has not negatively impaired the sensing sensitivity of the glucose sensor if and only if its thickness was sufficiently small. This implication of this work can be advantageously used to tailor the future invivo glucose methodology or other health-care electronic devices.