This work presents a noninvasive measurement technique to detect the blood glucose level for diabetic individuals using a fractal microwave resonator printed on an FR-4 substrate. The proposed fractal is based on the 1st order of Minkowski open loops (MOL) coupled with an open-stub transmission line (OSTL) to increase the resonator selectivity at 2.45 GHz. Moreover, an air gap in the middle path of the OSTL is filed with multi wall carbon nanotubes patch (CNT) to increase the field fringing at a specific region. The proposed resonator is designed numerically with CST Microwave Studio. The size limitations for biomedical devices are considered to account for wearable applications. Later, an analytical study is presented on the proposed resonator sensitivity. The detection technique is based on the resonant frequency tuning, bandwidth variation, impedance matching change, and phase displacement for the S-parameters in the S11 and S12 spectra. The sample under test is mounted on an CNT patch of the OSTL which employs the characterization of the specimen. The proposed design idea could be generalized for a wide variety of biomedical detection liquids.
2. Lee, C.-S. and C.-L. Yang, "Complementary split-ring resonators for measuring dielectric constants and loss tangents," IEEE Microw. Wireless Compon. Lett., Vol. 24, No. 8, 563-565, Aug. 2014.
3. Yang, C.-L., C.-S. Lee, K.-W. Chen, and K.-Z. Chen, "Noncontact measurement of complex permittivity and thickness by using planar resonators," IEEE Trans. Microw. Theory Techn., Vol. 64, No. 1, 247-257, Jan. 2016.
4. Naqui, J., C. Damm, A. Wiens, R. Jakoby, L. Su, J. Mata-Contreras, and F. Martın, "Transmission lines loaded with pairs of stepped impedance resonators: Modeling and application to differential permittivity measurements," IEEE Trans. Microw. Theory Techn., Vol. 64, No. 11, 3864-3877, Oct. 4, 2016.
5. Puentes, M., C. Weiß, M. Schußler, and R. Jakoby, "Sensor array based on split ring resonators for analysis of organic tissues," IEEE MTT-S Int. Microw. Symp. Dig., 1-4, Baltimore, MD, USA, Jun. 2011.
6. Puentes, M., Planar Metamaterial Based Microwave Sensor Arrays for Biomedical Analysis and Treatment, Springer, Heidelberg, Germany, 2014.
7. Hardinata, S., F. Deshours, G. Alquie, H. Kokabi, and F. Koskas, "Miniaturization of microwave biosensor for non-invasive measurements of materials and biological tissues," IPTEK Journal of Proceedings Series, Vol. 1, 90-93, Jan. 29, 2018.
8. Chretiennot, T., D. Dubuc, and K. Grenier, "A microwave and microfluidic planar resonator for efficient and accurate complex permittivity characterization of aqueous solutions," IEEE Trans. Microw. Theory Techn., Vol. 61, No. 2, 972-978, Feb. 2013.
9. Elwi, T. A. and W. J. Khudhayer, "A passive wireless gas sensor based on microstrip antenna with copper nanorods," Progress In Electromagnetics Research B, Vol. 55, 347-364, 2013.
10. Ebrahimi, A., W. Withayachumnankul, S. Al-Sarawi, and D. Abbott, "High-sensitivity metamaterial-inspired sensor for microfluidic dielectric characterization," IEEE Sensors J., Vol. 14, No. 5, 1345-1351, May 2014.
11. Withayachumnankul, W., K. Jaruwongrungsee, A. Tuantranont, C. Fumeaux, and D. Abbott, "Metamaterial-based microfluidic sensor for dielectric characterization," Sens. Actuators A: Phys., Vol. 189, 233-237, Jan. 2013.
12. Lee, H.-J. and J.-G. Yook, "Biosensing using split-ring resonators at microwave regime," Appl. Phys. Lett., Vol. 92, No. 25, 254103, 2008.
13. Grenier, K., et al., "Integrated broadband microwave and microfluidic sensor dedicated to bioengineering," IEEE Trans. Microw. Theory Techn., Vol. 57, No. 12, 3246-3253, Dec. 2009.
14. Chen, T., D. Dubuc, and K. Grenier, "Resonant-based microwave biosensor for physiological liquid identification," Proc. Eur. Microw. Conf., 448-450, Amsterdam, The Netherland, Oct./Nov. 2012.
15. Chretiennot, T., D. Dubuc, and K. Grenier, "Optimized electromagnetic interaction microwave resonator/microfluidic channel for enhanced liquid bio-sensor," Proc. Eur. Microw. Conf., 464-467, Nuremberg, Germany, Oct. 2013.
16. Chretiennot, T., D. Dubuc, and K. Grenier, "Double stub resonant biosensor for glucose concentrations quantification of multiple aqueous solutions," IEEE MTT-S Int. Microw. Symp. Dig., 1-4, Tampa, FL, USA, Jun. 2014.
17. Ekmekci, E. and G. Turhan-Sayan, "Multi-functional metamaterial sensor based on a broad-side coupled SRR topology with a multi-layer substrate," Appl. Phys. A, Solids Surf., Vol. 110, No. 1, 189-197, Jan. 2013.
18. Wongkasem, N. and M. Ruiz, "Multi-negative index band metamaterial-inspired microfluidic sensors," Progress In Electromagnetics Research C, Vol. 94, 29-41, 2019.
19. Damm, C., M. Schußler, M. Puentes, H. Maune, M. Maasch, and R. Jakoby, "Artificial transmission lines for high sensitive microwave sensors," Proc. IEEE Sensors Conf., 755-758, Christchurch, New Zealand, Oct. 2009.
20. Damm, C., Artificial Transmission Line Structures for Tunable Microwave Components and Microwave Sensors, Shaker Verlag, Aachen, Germany, 2011.
21. Turgul, V. and I. Kale, "Permittivity extraction of glucose solutions through artificial neural networks and non-invasive microwave glucose sensing," Sens. Actuators A: Phys., Vol. 277, 65-72, 2018.
22. Turgul, V. and I. Kale, "Sensitivity of non-invasive RF/microwave glucose sensors and fundamental factors and challenges affecting measurement accuracy," Proceedings of the 2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 1-5, Houston, TX, USA, May 14–17, 2018.