Preliminary Feasibility Study of Glucose Sensing by Permittivity Measurements in the RF Range

Continuous blood glucose monitoring is an essential need for diabetes patients. The preferred modality for glucose sensing would be non-invasive. Permittivity of a material can be measured non-invasively, and it depends on the material constituents. Accordingly, it has been proposed that glucose concentration could be measured by measuring the permittivity of the biofluids. However, the relevance of permittivity as a biomarker depends on the permittivity contrast between various physiological concentrations of glucose. In order to examine the feasibility of such sensing in the radiofrequency (RF) range, we measured the permittivity of glucose solutions in physiological saline. The results show that the permittivity variation within the physiological range of glucose concentrations is too low to be detectable using the open-ended coaxial probe below a few GHz. The results contribute to the understanding of the limitations of blood glucose monitoring by permittivity measurements using an open-ended coaxial probe.