{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T16:19:45Z","timestamp":1787761185513,"version":"build-2784847793"},"reference-count":32,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2022,5,25]],"date-time":"2022-05-25T00:00:00Z","timestamp":1653436800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Painless, cuffless and continuous blood pressure monitoring sensors provide a more dynamic measure of blood pressure for critical diagnosis or continuous monitoring of hypertensive patients compared to current cuff-based options. To this end, a novel flexible, wearable and miniaturized microstrip patch antenna topology is proposed to measure dynamic blood pressure (BP). The methodology was implemented on a simulated five-layer human tissue arm model created and designed in High-Frequency Simulation Software \u201cHFSS\u201d. The electrical properties of the five-layer human tissue were set at the frequency range (2\u20133) GHz to comply with clinical\/engineering standards. The fabricated patch incorporated on a 0.4 mm epoxy substrate achieved consistency between the simulated and measured reflection coefficient results at flat and bent conditions over the frequency range of 2.3\u20132.6 GHz. Simulations for a 10 g average specific absorption rate (SAR) based on IEEE-Standard for a human arm at different input powers were also carried out. The safest input power was 50 mW with an acceptable SAR value of 3.89 W\/Kg &lt; 4W\/Kg. This study also explored a novel method to obtain the pulse transit time (PTT) as an option to measure BP. Pulse transmit time is based on obtaining the time difference between the transmission coefficient scattering waveforms measured between the two pairs of metallic sensors underlying the assumption that brachial arterial geometries are dynamic. Consequently, the proposed model is validated by comparing it to the standard nonlinear Moens and Korteweg model over different artery thickness-radius ratios, showing excellent correlation between 0.76 \u00b1 0.03 and 0.81 \u00b1 0.03 with the systolic and diastolic BP results. The absolute risk of arterial blood pressure increased with the increase in brachial artery thickness-radius ratio. The results of both methods successfully demonstrate how the radius estimates, PTT and pulse wave velocity (PWV), along with electromagnetic (EM) antenna transmission propagation characteristics, can be used to estimate continuous BP non-invasively.<\/jats:p>","DOI":"10.3390\/s22113996","type":"journal-article","created":{"date-parts":[[2022,5,25]],"date-time":"2022-05-25T08:41:33Z","timestamp":1653468093000},"page":"3996","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Wearable Blood Pressure Sensing Based on Transmission Coefficient Scattering for Microstrip Patch Antennas"],"prefix":"10.3390","volume":"22","author":[{"given":"Mona K.","family":"El Abbasi","sequence":"first","affiliation":[{"name":"Electrical and Computer Engineering Department, American University of Beirut, Beirut 1107 2020, Lebanon"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3435-9890","authenticated-orcid":false,"given":"Mervat","family":"Madi","sequence":"additional","affiliation":[{"name":"Electrical and Electronics Engineering School Department, Amity University Dubai, Dubai P.O. Box 345019, United Arab Emirates"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Herbert F.","family":"Jelinek","sequence":"additional","affiliation":[{"name":"Biomedical Engineering Department and Health Innovation Engineering Center, Biotechnology Center, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karim Y.","family":"Kabalan","sequence":"additional","affiliation":[{"name":"Electrical and Computer Engineering Department, American University of Beirut, Beirut 1107 2020, Lebanon"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1136\/adc.82.3.261","article-title":"Current topic: Measurement and interpretation of Blood Pressure","volume":"82","author":"Goonasekera","year":"2000","journal-title":"Arch. Dis. Child."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"231","DOI":"10.3389\/fmed.2017.00231","article-title":"Techniques for non-invasive monitoring of arterial blood pressure","volume":"4","author":"Meidert","year":"2018","journal-title":"Front. Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"353","DOI":"10.3109\/08037051.2015.1053253","article-title":"Blood pressure monitoring during exercise: Comparison of pulse transit time and volume clamp methods","volume":"24","author":"Wibmer","year":"2015","journal-title":"Blood Press."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Hellbr\u00fcck, H., Ardelt, G., Wegerich, P., and Gehring, H. (2020). Brachialis pulse Wave measurements with ultra-wide band and continuous wave radar, Photoplethysmography and Ultrasonic Doppler Sensors. Sensors, 21.","DOI":"10.3390\/s21010165"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1109\/5.119564","article-title":"Antenna theory: A review","volume":"80","author":"Balanis","year":"1992","journal-title":"Proc. IEEE"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Yao, J., Xu, C.C., Mears, A., Jaguan, M., Tjuatja, S., and Huang, H. (2015). Pressure sensing using low-cost microstrip antenna sensor. Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, International Society for Optics and Photonics.","DOI":"10.1117\/12.2084283"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Kim, I., and Bhagat, Y.A. (2016, January 16\u201320). Towards development of a Mobile RF Doppler sensor for continuous heart rate variability and blood pressure monitoring. Proceedings of the 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Orlando, FL, USA.","DOI":"10.1109\/EMBC.2016.7591455"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Wang, R., Jia, W., Mao, Z.-H., Sclabassi, R.J., and Sun, M. (2014, January 19\u201323). Cuff-free blood pressure estimation using pulse transit time and heart rate. Proceedings of the 12th International Conference on Signal Processing (ICSP), Hangzhou, China.","DOI":"10.1109\/ICOSP.2014.7014980"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1879","DOI":"10.1109\/TBME.2015.2441951","article-title":"Toward ubiquitous blood pressure monitoring via pulse transit time: Theory and practice","volume":"62","author":"Mukkamala","year":"2015","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Huynh, T., Jafari, R., and Chung, W.-Y. (2018). An accurate bioimpedance measurement system for Blood Pressure monitoring. Sensors, 18.","DOI":"10.3390\/s18072095"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Kathuria, N., and Seet, B.-C. (2021). 24 GHz flexible antenna for doppler radar-based human vital signs monitoring. Sensors, 21.","DOI":"10.3390\/s21113737"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"7546","DOI":"10.3390\/s130607546","article-title":"Accurate human tissue characterization for energy-efficient wireless on-body communications","volume":"13","author":"Vallejo","year":"2013","journal-title":"Sensors"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1016\/j.atherosclerosis.2017.11.022","article-title":"Brachial artery diameter as a marker for cardiovascular risk assessment: FMD-J Study","volume":"268","author":"TMaruhashi","year":"2018","journal-title":"Atherosclerosis"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"515","DOI":"10.1038\/sj.jhh.1000475","article-title":"Parallel increase in carotid, brachial and left ventricular cross-sectional areas in arterial hypertension","volume":"11","author":"Fantini","year":"1997","journal-title":"J. Hum. Hypertens."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Abohmra, A., Ramani, S., Sharif, A., Imran, M.A., Abbasi, Q., and Ahmad, W. (2019, January 5\u20138). Novel flexible and wearable 2.4 GHz antenna for body-centric applications. Proceedings of the 2019 IEEE Intl Conf on Dependable, Autonomic and Secure Computing, Intl Conf on Pervasive Intelligence and Computing, Intl Conf on Cloud and Big Data Computing, Intl Conf on Cyber Science and Technology Congress (DASC\/PiCom\/CBDCom\/CyberSciTech), Fukuoka, Japan.","DOI":"10.1109\/DASC\/PiCom\/CBDCom\/CyberSciTech.2019.00082"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"261","DOI":"10.2528\/PIER06040601","article-title":"EM energy absorption in the human body tissues due to UWB antennas","volume":"62","author":"Klemm","year":"2006","journal-title":"Prog. Electromagn. Res."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1002\/mrm.24671","article-title":"Thermal tissue damage model analyzed for different whole-body SAR and scan durations for standard body coils","volume":"71","author":"Murbach","year":"2013","journal-title":"Magn. Reson. Med."},{"key":"ref_18","unstructured":"(2019). IEEE Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic, and Electromagnetic Fields, 0 Hz to 300 GHz. (n.d.) (Standard No. C95.1-2019)."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Ali, I.H., Hamd, H.I., and Abdalla, A.I. (April, January 6). Design and comparison of two types of antennas for SAR calculation in wireless applications. Proceedings of the 2018 Advances in Science and Engineering Technology International Conferences (ASET), Dubai, Sharjah, Abu Dhabi, United Arab Emirates.","DOI":"10.1109\/ICASET.2018.8376891"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Lin, H.D., Lee, Y.S., and Chuang, B.N. (September, January 28). Using dual-antenna nanosecond pulse near-field sensing technology for non-contact and continuous blood pressure measurement. Proceedings of the 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, San Diego, CA, USA.","DOI":"10.1109\/EMBC.2012.6345909"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"16346","DOI":"10.1038\/s41598-019-52710-8","article-title":"Blood pressure estimation using on-body continuous wave radar and photoplethysmogram in various posture and exercise conditions","volume":"9","author":"Ebrahim","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"851","DOI":"10.1007\/s00431-020-03785-3","article-title":"Vascular diameter and intima-media thickness to diameter ratio values of the carotid artery in 642 healthy children","volume":"180","author":"Semmler","year":"2020","journal-title":"Eur. J. Pediatr."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1177\/1358863X09105132","article-title":"Brachial artery diameter, blood flow and flow-mediated dilation in sleep-disordered breathing","volume":"14","author":"Chami","year":"2009","journal-title":"Vasc. Med."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1719","DOI":"10.1093\/eurheartj\/eht565","article-title":"Central blood pressure: Current evidence and clinical importance","volume":"35","author":"McEniery","year":"2014","journal-title":"Eur. Heart J."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"802","DOI":"10.1067\/mhj.2002.121735","article-title":"Large brachial artery diameter is associated with angiographic coronary artery disease in women","volume":"143","author":"Holubkov","year":"2002","journal-title":"Am. Heart J."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Kachuee, M., Kiani, M.M., Mohammadzade, H., and Shabany, M. (2015, January 24\u201327). Cuff-less high-accuracy calibration-free blood pressure estimation using Pulse Transit Time. Proceedings of the 2015 IEEE International Symposium on Circuits and Systems (ISCAS), Lisbon, Portugal.","DOI":"10.1109\/ISCAS.2015.7168806"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"H1389","DOI":"10.1152\/ajpheart.00443.2011","article-title":"Improved pulse transit time estimation by system identification analysis of proximal and distal arterial waveforms","volume":"301","author":"Xu","year":"2011","journal-title":"Am. J. Physiol.-Heart Circ. Physiol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1524","DOI":"10.1109\/TBME.2016.2612639","article-title":"Estimation of pulse transit time as a function of blood pressure using a nonlinear arterial tube-load model","volume":"64","author":"Gao","year":"2017","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1007\/s13534-019-00096-x","article-title":"Pulse Transit Time technique for cuffless unobtrusive blood pressure measurement: From theory to algorithm","volume":"9","author":"Ding","year":"2019","journal-title":"Biomed. Eng. Lett."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"e007621","DOI":"10.1161\/JAHA.117.007621","article-title":"Relationship of arterial stiffness index and pulse pressure with cardiovascular disease and mortality","volume":"7","author":"Said","year":"2018","journal-title":"J. Am. Heart Assoc."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"McCall, C., Rostosky, R., Wiard, R.M., Inan, O.T., Giovangrandi, L., Cuttino, C.M., and Kovacs, G.T. (2015, January 25\u201329). Noninvasive pulse transit time measurement for arterial stiffness monitoring in microgravity. Proceedings of the 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Milan, Italy.","DOI":"10.1109\/EMBC.2015.7319864"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"264","DOI":"10.1007\/s12265-012-9349-8","article-title":"Elastin in large artery stiffness and hypertension","volume":"5","author":"Wagenseil","year":"2012","journal-title":"J. Cardiovasc. Transl. Res."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/11\/3996\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:18:15Z","timestamp":1760138295000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/11\/3996"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,25]]},"references-count":32,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2022,6]]}},"alternative-id":["s22113996"],"URL":"https:\/\/doi.org\/10.3390\/s22113996","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,5,25]]}}}