{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,18]],"date-time":"2026-03-18T05:10:13Z","timestamp":1773810613672,"version":"3.50.1"},"reference-count":43,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2021,10,16]],"date-time":"2021-10-16T00:00:00Z","timestamp":1634342400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Education, Youth and Sports of the Czech Republic; Student Grant Competition of CTU","award":["LTC19031; SGS21\/179\/OHK4\/3T\/17"],"award-info":[{"award-number":["LTC19031; SGS21\/179\/OHK4\/3T\/17"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>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 (\u2220S21) 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\u00b0 per mmol\/L and unit cell to blood glucose concentration as measured by changes in \u2220S21. 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\u00b0 per mmol\/L at a frequency of 1.99 GHz, compared to only 0.48\u00b0 per mmol\/L for the MSTL sensor. The multi-cell MTM sensor has the potential to proceed with evaluation of human blood samples.<\/jats:p>","DOI":"10.3390\/s21206871","type":"journal-article","created":{"date-parts":[[2021,10,17]],"date-time":"2021-10-17T23:25:15Z","timestamp":1634513115000},"page":"6871","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Feasibility Evaluation of Metamaterial Microwave Sensors for Non-Invasive Blood Glucose Monitoring"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2953-1035","authenticated-orcid":false,"given":"Lukas","family":"Malena","sequence":"first","affiliation":[{"name":"Faculty of Biomedical Engineering, Czech Technical University in Prague, 160 00 Prague, Czech Republic"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8259-0611","authenticated-orcid":false,"given":"Ondrej","family":"Fiser","sequence":"additional","affiliation":[{"name":"Faculty of Biomedical Engineering, Czech Technical University in Prague, 160 00 Prague, Czech Republic"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paul R.","family":"Stauffer","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA 19107, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9061-8231","authenticated-orcid":false,"given":"Tomas","family":"Drizdal","sequence":"additional","affiliation":[{"name":"Faculty of Biomedical Engineering, Czech Technical University in Prague, 160 00 Prague, Czech Republic"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6528-0187","authenticated-orcid":false,"given":"Jan","family":"Vrba","sequence":"additional","affiliation":[{"name":"Faculty of Biomedical Engineering, Czech Technical University in Prague, 160 00 Prague, Czech Republic"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8631-4283","authenticated-orcid":false,"given":"David","family":"Vrba","sequence":"additional","affiliation":[{"name":"Faculty of Biomedical Engineering, Czech Technical University in Prague, 160 00 Prague, Czech Republic"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,10,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Wilkinson, I.B., Raine, T., Wiles, K., Goodhart, A., Hall, C., and O\u2019Neill, H. (2017). Oxford Handbook of Clinical Medicine, OUP Oxford. [10th ed.].","DOI":"10.1093\/med\/9780199689903.001.0001"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1109\/RBME.2018.2822301","article-title":"Pain-Free Blood Glucose Monitoring Using Wearable Sensors: Recent Advancements and Future Prospects","volume":"11","author":"Siddiqui","year":"2018","journal-title":"IEEE Rev. Biomed. Eng."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"14790","DOI":"10.1038\/s41598-020-71908-9","article-title":"Global, Regional, and National Burden and Trend of Diabetes in 195 Countries and Territories: An Analysis from 1990 to 2025","volume":"10","author":"Lin","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Tasker, R.C., Acerini, C.L., Holloway, E., Shah, A., and Lillitos, P. (2021). Oxford Handbook of Paediatrics, Oxford University Press. [3rd ed.].","DOI":"10.1093\/med\/9780198789888.001.0001"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Bruen, D., Delaney, C., Florea, L., and Diamond, D. (2017). Glucose Sensing for Diabetes Monitoring: Recent Developments. Sensors, 17.","DOI":"10.3390\/s17081866"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Tang, L., Chang, S.J., Chen, C.-J., and Liu, J.-T. (2020). Non-Invasive Blood Glucose Monitoring Technology: A Review. Sensors, 20.","DOI":"10.3390\/s20236925"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Jang, C., Lee, H.-J., and Yook, J.-G. (2021). Radio-Frequency Biosensors for Real-Time and Continuous Glucose Detection. Sensors, 21.","DOI":"10.3390\/s21051843"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Yilmaz, T., Foster, R., and Hao, Y. (2019). Radio-Frequency and Microwave Techniques for Non-Invasive Measurement of Blood Glucose Levels. Diagnostics, 9.","DOI":"10.3390\/diagnostics9010006"},{"key":"ref_9","unstructured":"(2021). GlucoTrack\u00ae, Your Track to Health!, Integrity Applications. DF-F."},{"key":"ref_10","unstructured":"(2021, August 15). CoG\u2014Hybrid Glucometer|Cnoga Digital Care. Available online: https:\/\/www.cnogacare.co\/cog-hybrid-glucometer."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1177\/1932296820947112","article-title":"Proof of Concept for a New Raman-Based Prototype for Noninvasive Glucose Monitoring","volume":"15","author":"Pleus","year":"2021","journal-title":"J. Diabetes Sci. Technol."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Lundsgaard-Nielsen, S.M., Pors, A., Banke, S.O., Henriksen, J.E., Hepp, D.K., and Weber, A. (2018). Critical-Depth Raman Spectroscopy Enables Home-Use Non-Invasive Glucose Monitoring. PLoS ONE, 13.","DOI":"10.1371\/journal.pone.0197134"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2231","DOI":"10.1088\/0031-9155\/41\/11\/001","article-title":"The Dielectric Properties of Biological Tissues: I. Literature Survey","volume":"41","author":"Gabriel","year":"1996","journal-title":"Phys. Med. Biol."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Beam, K., and Venkataraman, J. (2011, January 3\u20138). Phantom Models for In-Vitro Measurements of Blood Glucose. Proceedings of the 2011 IEEE International Symposium on Antennas and Propagation (APSURSI), Spokane, WA, USA.","DOI":"10.1109\/APS.2011.5996860"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1160","DOI":"10.1002\/mop.27515","article-title":"Cole-Cole Model for Glucose-Dependent Dielectric Properties of Blood Plasma for Continuous Glucose Monitoring","volume":"55","author":"Karacolak","year":"2013","journal-title":"Microw. Opt. Technol. Lett."},{"key":"ref_16","first-page":"45","article-title":"Recent Advances in Noninvasive Glucose Monitoring","volume":"5","author":"So","year":"2012","journal-title":"Med. Devices Auckl. NZ"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2195","DOI":"10.1109\/TMTT.2013.2250516","article-title":"Microwave-Based Noninvasive Concentration Measurements for Biomedical Applications","volume":"61","author":"Hofmann","year":"2013","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"369","DOI":"10.1088\/0022-3727\/36\/4\/307","article-title":"Dielectric Spectroscopy Study of Specific Glucose Influence on Human Erythrocyte Membranes","volume":"36","author":"Hayashi","year":"2003","journal-title":"J. Phys. Appl. Phys."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Freer, B., and Venkataraman, J. (2010, January 11\u201317). Feasibility Study for Non-Invasive Blood Glucose Monitoring. Proceedings of the 2010 IEEE Antennas and Propagation Society International Symposium (APSURSI), Toronto, ON, Canada.","DOI":"10.1109\/APS.2010.5561003"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1109\/JSEN.2018.2877691","article-title":"Microstrip Line-Based Glucose Sensor for Noninvasive Continuous Monitoring Using the Main Field for Sensing and Multivariable Crosschecking","volume":"19","author":"Huang","year":"2019","journal-title":"IEEE Sens. J."},{"key":"ref_21","unstructured":"Yilmaz, T., Ozturk, T., and Joof, S. (2017, January 19\u201326). A Comparative Study for Development of Microwave Glucose Sensors. Proceedings of the 32nd URSI General Assembly and Scientific Symposium (URSI GASS 2017), Montreal, QC, Canada."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Saleh, G., Ateeq, I.S., and Al-Naib, I. (2021). Glucose Level Sensing Using Single Asymmetric Split Ring Resonator. Sensors, 21.","DOI":"10.3390\/s21092945"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Odabashyan, L., Babajanyan, A., Baghdasaryan, Z., Kim, S., Kim, J., Friedman, B., Lee, J.-H., and Lee, K. (2019). Real-Time Noninvasive Measurement of Glucose Concentration Using a Modified Hilbert Shaped Microwave Sensor. Sensors, 19.","DOI":"10.3390\/s19245525"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Kumar, A., Wang, C., Meng, F.-Y., Zhou, Z.-L., Zhao, M., Yan, G.-F., Kim, E.-S., and Kim, N.-Y. (2020). High-Sensitivity, Quantified, Linear and Mediator-Free Resonator-Based Microwave Biosensor for Glucose Detection. Sensors, 20.","DOI":"10.3390\/s20144024"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"404","DOI":"10.1109\/JSTQE.2017.2659226","article-title":"Cost-Effective, Microstrip Antenna Driven Ring Resonator Microwave Biosensor for Biospecific Detection of Glucose","volume":"23","author":"Camli","year":"2017","journal-title":"IEEE J. Sel. Top. Quantum Electron."},{"key":"ref_26","unstructured":"Sidley, M. (2013). Calibration for Real-Time Non-Invasive Blood Glucose Monitoring. [Ph.D. Thesis, Rochester Institute of Technology]."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"942","DOI":"10.1109\/LMWC.2018.2861565","article-title":"T-Shaped Patterned Microstrip Line for Noninvasive Continuous Glucose Sensing","volume":"28","author":"Omkar","year":"2018","journal-title":"IEEE Microw. Wirel. Compon. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Zeising, S., Kirchner, J., Khalili, H.F., Ahmed, D., L\u00fcbke, M., Thalmayer, A., and Fischer, G. (2021). Towards Realisation of a Non-Invasive Blood Glucose Sensor Using Microstripline. TechRxiv, preprint.","DOI":"10.36227\/techrxiv.13553528"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"877","DOI":"10.13164\/re.2015.0877","article-title":"A Microwave Metamaterial Inspired Sensor for Non-Invasive Blood Glucose Monitoring","volume":"24","author":"Vrba","year":"2015","journal-title":"Radioengineering"},{"key":"ref_30","unstructured":"Pozar, D.M. (1998). Microwave Engineering, John Wiley and Sons. [2nd ed.]."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Damm, C., Schussler, M., Puentes, M., Maune, H., Maasch, M., and Jakoby, R. (2009, January 25\u201328). Artificial Transmission Lines for High Sensitive Microwave Sensors. Proceedings of the 2009 IEEE Sensors, Christchurch, New Zealand.","DOI":"10.1109\/ICSENS.2009.5398538"},{"key":"ref_32","unstructured":"Vrba, J., Vrba, D., D\u00edaz, L., and Fi\u0161er, O. (2021, June 25). Metamaterial Sensor for Microwave Non-invasive Blood Glucose Monitoring. Available online: https:\/\/www.springerprofessional.de\/metamaterial-sensor-for-microwave-non-invasive-blood-glucose-mon\/15802180."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"3064","DOI":"10.1109\/TAP.2014.2313139","article-title":"Broadband Tissue Mimicking Phantoms and a Patch Resonator for Evaluating Noninvasive Monitoring of Blood Glucose Levels","volume":"62","author":"Yilmaz","year":"2014","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Adhyapak, A., Sidley, M., and Venkataraman, J. (2014, January 26\u201330). Analytical Model for Real Time, Noninvasive Estimation of Blood Glucose Level. Proceedings of the 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society EMBC 2014, Chicago, IL, USA.","DOI":"10.1109\/EMBC.2014.6944752"},{"key":"ref_35","unstructured":"(2021, August 15). DAK \u00bb SPEAG, Schmid & Partner Engineering AG. Available online: https:\/\/speag.swiss\/products\/dak\/dak-probes\/."},{"key":"ref_36","unstructured":"(2021, August 15). R&S\u00aeZNB Vector Network Analyzer. Available online: https:\/\/www.rohde-schwarz.com\/pl\/products\/test-and-measurement\/network-analyzers\/rs-znb-vector-network-analyzer_63493-11648.html."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"570","DOI":"10.1112\/jlms\/s1-43.1.570b","article-title":"Lectures on curves on an algebraic surface: A book review","volume":"s1-43","author":"Tyrrell","year":"1968","journal-title":"J. Lond. Math. Soc."},{"key":"ref_38","unstructured":"(2018). Ro4000-Laminates-Ro4003c-and-Ro4350b-Data-Sheet, Rogers Corporation."},{"key":"ref_39","unstructured":"(2017). I-Tera Mt40 Data Sheet, Isola Group."},{"key":"ref_40","unstructured":"(2021, August 15). PLA\u2014Prusa Research. Available online: https:\/\/shop.prusa3d.com\/en\/21-pla."},{"key":"ref_41","unstructured":"COMSOL (2019). Multiphysics Reference Manual 2019, COMSOL Inc."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Pham, H. (2019). A New Criterion for Model Selection. Mathematics, 7.","DOI":"10.3390\/math7121215"},{"key":"ref_43","unstructured":"Hasgall, P.A., di Gennaro, F., Baumgartner, C., Neufeld, E., Lloyd, B., Gosselin, M.C., Payne, D., Klingenboeck, A., and Kuster, N. (2018). Tissue Properties Database V4.0 2018, IT\u2019IS Foundation."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/20\/6871\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:16:10Z","timestamp":1760166970000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/20\/6871"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,10,16]]},"references-count":43,"journal-issue":{"issue":"20","published-online":{"date-parts":[[2021,10]]}},"alternative-id":["s21206871"],"URL":"https:\/\/doi.org\/10.3390\/s21206871","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,10,16]]}}}