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. 2021 Oct 16;21(20):6871.
doi: 10.3390/s21206871.

Feasibility Evaluation of Metamaterial Microwave Sensors for Non-Invasive Blood Glucose Monitoring

Lukas Malena  1 , Ondrej Fiser  1 , Paul R Stauffer  2 , Tomas Drizdal  1 , Jan Vrba  1 , David Vrba  1
Affiliations

Feasibility Evaluation of Metamaterial Microwave Sensors for Non-Invasive Blood Glucose Monitoring

Lukas Malena et al. Sensors (Basel). .

Abstract

The use of microwave technology is currently under investigation for non-invasive estimation of glycemia in patients with diabetes. Due to their construction, metamaterial (MTM)-based sensors have the potential to provide higher sensitivity of the phase shift of the S21 parameter (∠S21) to changes in glucose concentration compared to standard microstrip transmission line (MSTL)-based sensors. In this study, a MSTL sensor and three MTM sensors with 5, 7, and 9 MTM unit cells are exposed to liquid phantoms with different dielectric properties mimicking a change in blood glucose concentration from 0 to 14 mmol/L. Numerical models were created for the individual experiments, and the calculated S-parameters show good agreement with experimental results, expressed by the maximum relative error of 8.89% and 0.96% at a frequency of 1.99 GHz for MSTL and MTM sensor with nine unit cells, respectively. MTM sensors with an increasing number of cells show higher sensitivity of 0.62° per mmol/L and unit cell to blood glucose concentration as measured by changes in ∠S21. In accordance with the numerical simulations, the MTM sensor with nine unit cells showed the highest sensitivity of the sensors proposed by us, with an average of 3.66° per mmol/L at a frequency of 1.99 GHz, compared to only 0.48° per mmol/L for the MSTL sensor. The multi-cell MTM sensor has the potential to proceed with evaluation of human blood samples.

Keywords: dielectric properties; glucose monitoring; microwave sensor.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Geometries and photographs of sensors. Geometries of (A) MTM9 and (B) MSTL sensors. Photographs of (C) MTM9 and (D) MSTL sensor.
Figure 2
Figure 2
Tailor-made holder with MTM9 sensor in PLA box ready for measurement.
Figure 3
Figure 3
Computational domain geometry; (A) and (B) are perspective and top view of the computational domain geometry, respectively. (C) and (D) are detailed views of the cross-sections in xz and yz planes with dimensions in mm.
Figure 4
Figure 4
Measured values of relative permittivity.
Figure 5
Figure 5
Measured values of electrical conductivity.
Figure 6
Figure 6
The course of ∠S21 for all tested sensors.
Figure 7
Figure 7
The course of ∠S21 for MSTL and 4 mL.
Figure 8
Figure 8
Detail of MSTL at 1.99 GHz and 4 mL.
Figure 9
Figure 9
The course of ∠S21 for MTM9 and 4 mL.
Figure 10
Figure 10
Detail of MTM9 at 1.99 GHz and 4 mL.
See this image and copyright information in PMC

References

    1. Wilkinson I.B., Raine T., Wiles K., Goodhart A., Hall C., O’Neill H. Oxford Handbook of Clinical Medicine. 10th ed. OUP Oxford; Oxford, UK: 2017.
    1. Siddiqui S.A., Zhang Y., Lloret J., Song H., Obradovic Z. Pain-Free Blood Glucose Monitoring Using Wearable Sensors: Recent Advancements and Future Prospects. IEEE Rev. Biomed. Eng. 2018;11:21–35. doi: 10.1109/RBME.2018.2822301. - DOI - PubMed
    1. Lin X., Xu Y., Pan X., Xu J., Ding Y., Sun X., Song X., Ren Y., Shan P.-F. Global, Regional, and National Burden and Trend of Diabetes in 195 Countries and Territories: An Analysis from 1990 to 2025. Sci. Rep. 2020;10:14790. doi: 10.1038/s41598-020-71908-9. - DOI - PMC - PubMed
    1. Tasker R.C., Acerini C.L., Holloway E., Shah A., Lillitos P. Oxford Handbook of Paediatrics. 3rd ed. Oxford University Press; Oxford, UK: 2021.
    1. Bruen D., Delaney C., Florea L., Diamond D. Glucose Sensing for Diabetes Monitoring: Recent Developments. Sensors. 2017;17:1866. doi: 10.3390/s17081866. - DOI - PMC - PubMed