In this article, which is a fundamental step in an underway research, a microwave resonant sensor at two resonance frequencies of 5.5 and 8.5 GHz (in order to increase the accuracy of the application) with a quality factor of 180 and 106, for blood glucose level monitoring is designed, fabricated, and tested by users' fingertips. In this study, 11 volunteers were tested invasively (using a glucometer) and noninvasively (using the proposed glucose resonant sensor) with range of glucose-level changes from 89 to 262 mg/dL. For this range of glucose-level changes, the frequency detection resolution is 3.53 and 3.58 MHz/ (mg/dL), respectively. The results of the experiments are relatively well matched; so that compared to the glucometer device, the proposed sensor shows a maximum measurement error of about 3% to detect glucose levels.

In this paper, a planar microstrip sensor based on band-stop filter for determining relative permittivity of solid materials is presented. The proposed sensor has been composed from the structure of meandered microstrip line with T-shaped resonator and an interdigital structure that is connected ground by via. Interaction between T-shaped resonator and interdigital structure is caused to increase electric field intensity and the high field increase the sensor sensitivity and resolution. The microwave sensor by using single layer technology is fabricated on the substrate RO4003. The samples of FR4 and RO4350 in single and double layer forms as multilayer is placed on the sensor and the sensor are demonstrating different resonance frequencies. The relationship between changing the resonance frequency and variation of the relative permittivity is linear and it determines unknown materials dielectric characterizations. The permittivity of samples changes from 3 to 11 therefore the resonance frequency varies from 3.7 GHz to 5.65 GHz to linearly. The proposed sensor shows improvement relative to other similar works in the fields of sensitivity and quality factor.