{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,15]],"date-time":"2026-06-15T01:42:29Z","timestamp":1781487749426,"version":"3.54.1"},"reference-count":40,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2023,10,9]],"date-time":"2023-10-09T00:00:00Z","timestamp":1696809600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Slovenian Research Agency","award":["P2-0225"],"award-info":[{"award-number":["P2-0225"]}]},{"name":"Slovenian Research Agency","award":["P2-0250"],"award-info":[{"award-number":["P2-0250"]}]},{"name":"Slovenian Research Agency","award":["54814-MR"],"award-info":[{"award-number":["54814-MR"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>There is a worldwide need to improve blood pressure (BP) measurement error in order to correctly diagnose hypertension. Cardiovascular diseases cause 17.9 million deaths annually and are a substantial monetary strain on healthcare. The current measurement uncertainty of 3 mmHg should be improved upon. Dynamic pressure measurement standards are lacking or non-existing. In this study we propose a novel method of measuring air pressure inside the sphygmomanometer tubing during BP measurement using a condenser microphone. We designed, built, and tested a system that uses a radiofrequency (RF) modulation method to convert changes in capacitance of a condenser microphone into pressure signals. We tested the RF microphone with a low-frequency (LF) sound source, BP simulator and using a piezoresistive pressure sensor as a reference. Necessary tests were conducted to assess the uncertainty budget of the system. The RF microphone prototype has a working frequency range from 0.5 Hz to 280 Hz in the pressure range from 0 to 300 mmHg. The total expanded uncertainty (k = 2, p = 95.5%) of the RF microphone was 4.32 mmHg. The proposed method could establish traceability of BP measuring devices to acoustic standards described in IEC 61094-2 and could also be used in forming dynamic BP standards.<\/jats:p>","DOI":"10.3390\/s23198340","type":"journal-article","created":{"date-parts":[[2023,10,9]],"date-time":"2023-10-09T12:51:04Z","timestamp":1696855864000},"page":"8340","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Sphygmomanometer Dynamic Pressure Measurement Using a Condenser Microphone"],"prefix":"10.3390","volume":"23","author":[{"given":"\u017dan","family":"Tomazini","sequence":"first","affiliation":[{"name":"Faculty of Electrical Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1161-9197","authenticated-orcid":false,"given":"Gregor","family":"Ger\u0161ak","sequence":"additional","affiliation":[{"name":"Faculty of Electrical Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Samo","family":"Begu\u0161","sequence":"additional","affiliation":[{"name":"Faculty of Electrical Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,9]]},"reference":[{"key":"ref_1","unstructured":"(2023, July 20). World Health Organization. Available online: https:\/\/www.who.int\/health-topics\/cardiovascular-diseases."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2921","DOI":"10.1016\/j.jacc.2020.04.038","article-title":"Association of Age of Onset of Hypertension with Cardiovascular Diseases and Mortality","volume":"75","author":"Wang","year":"2020","journal-title":"J. Am. Coll. Cardiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1016\/j.phrs.2017.11.003","article-title":"Hypertension and cardiovascular risk: General aspects","volume":"Volume 129","author":"Kjeldsen","year":"2018","journal-title":"Pharmacological Research"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1097\/00126097-200410000-00004","article-title":"Effects of systematic errors in blood pressure measurements on the diagnosis of hypertension","volume":"9","author":"Turner","year":"2004","journal-title":"Blood Press. Monit."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1097\/MBP.0000000000000321","article-title":"Evaluating the impact of measurement uncertainty in blood pressure measurement on hypertension diagnosis","volume":"23","author":"Filho","year":"2018","journal-title":"Blood Press. Monit."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"587","DOI":"10.1038\/sj.jhh.1001241","article-title":"The extent and implications of sphygmomanometer calibration error in primary care","volume":"15","author":"Rouse","year":"2001","journal-title":"J. Hum. Hypertens."},{"key":"ref_7","first-page":"834","article-title":"Sphygmomanometer calibration\u2013why, how and how often?","volume":"36","author":"Turner","year":"2007","journal-title":"Aust. Fam. Physician"},{"key":"ref_8","unstructured":"Hjelmgren, J. (2002). Dynamic Measurement of Pressure\u2013A Literature Survey, SP Technical Research Institute of Sweden. SP Report."},{"key":"ref_9","unstructured":"Nilsson, M. (2016). Dynamic Calibration of Pressure Sensors, Lund University Department of Automatic Control. Available online: http:\/\/lup.lub.lu.se\/student-papers\/record\/8892670."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"747","DOI":"10.1088\/0026-1394\/30\/6\/039","article-title":"Development of a Primary Standard for the Measurement of Dynamic Pressure and Temperature","volume":"30","author":"Bean","year":"1994","journal-title":"Metrologia"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1278","DOI":"10.1121\/1.382112","article-title":"Theoretical response of condenser microphones","volume":"64","author":"Zuckerwar","year":"1978","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"224","DOI":"10.1016\/j.sna.2007.12.011","article-title":"Modeling and simulation of a condenser microphone","volume":"145\u2013146","author":"Chen","year":"2008","journal-title":"Sens. Actuators A Phys."},{"key":"ref_13","unstructured":"Weigold, J.W., Brosnihan, T.J., Bergeron, J., and Zhang, X. (2006, January 22\u201326). A MEMS Condenser Microphone for Consumer Applications. Proceedings of the 19th IEEE International Conference on Micro Electro Mechanical Systems, Istanbul, Turkey."},{"key":"ref_14","unstructured":"Lewis, J. (2023, July 20). Understanding Microphone Sensitivity. Available online: https:\/\/invensense.tdk.com\/wp-content\/uploads\/2015\/02\/Understanding-Microphone-Sensitivity3.pdf."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Niu, F., Zheng, A., Zhu, H., Yang, P., and He, L. (2012, January 5\u20138). Measurement of microphone parameters based on high-pressure calibration system. Proceedings of the IEEE 2012 IEEE International Conference on Mechatronics and Automation (ICMA), Chengdu, China.","DOI":"10.1109\/ICMA.2012.6283225"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"934","DOI":"10.1109\/JSEN.2009.2038230","article-title":"Design of a Low-Frequency Microphone for Mobile Phones and Its Application to Ubiquitous Medical and Healthcare Monitoring","volume":"10","author":"Watanabe","year":"2010","journal-title":"IEEE Sens. J."},{"key":"ref_17","unstructured":"(2023, July 20). Frequency Range of a Microphone. Available online: https:\/\/www.grasacoustics.com\/microphone-guide\/frequency-range."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Urbansky, L., and Zolzer, U. (2019, January 26\u201329). A Digital Radio-Frequency Condenser Microphone with Amplitude Modulation. Proceedings of the 2019 IEEE International Symposium on Circuits and Systems (ISCAS), Sapporo, Japan.","DOI":"10.1109\/ISCAS.2019.8702611"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Urbansky, L., and Zolzer, U. (2019, January 20\u201323). A Novel Digital Radio-Frequency Capacitor Microphone with Gain Ranging. Proceedings of the Audio Engineering Society Convention, Dublin, Ireland.","DOI":"10.1109\/ISCAS.2019.8702611"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1953","DOI":"10.1121\/10.0000946","article-title":"A high-quality digital radio-frequency capacitor microphone with improved dynamic range","volume":"147","author":"Urbansky","year":"2020","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_21","unstructured":"(2022). CSV Consolidated Version, Electroacoustics\u2013Measurement Microphones\u2013Part 2: Primary Method for Pressure Calibration of Laboratory Standard Microphones by the Reciprocity Technique (Standard No. IEC 61094-2:2009+AMD1:2022)."},{"key":"ref_22","unstructured":"Bouaoua, N., Fedtke, T., and Mellert, V. (2004, January 22\u201325). Feasibility study for a primary free-field microphone calibration technique in the frequency range 20 kHz to 200 kHz. Proceedings of the Joint Congress CFA\/DAGA\u201904, Strasbourg, France."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"012054","DOI":"10.1088\/1742-6596\/733\/1\/012054","article-title":"Primary calibration of measurement microphones in the world: State of art","volume":"733","author":"Milhomem","year":"2016","journal-title":"J. Phys. Conf. Ser."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1464","DOI":"10.1001\/jama.1950.02910520006004","article-title":"The Normal Blood Pressure Range and Its Clinical Implications","volume":"143","author":"Master","year":"1950","journal-title":"J. Am. Med. Assoc."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"257","DOI":"10.1186\/s13054-018-2171-1","article-title":"The meaning of blood pressure","volume":"22","author":"Magder","year":"2018","journal-title":"Crit. Care"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1001\/archinte.1939.00190030002001","article-title":"Range of Normal Blood Pressure: A Statistical and Clinical Study of 11,383 Persons","volume":"64","author":"Robinson","year":"1939","journal-title":"Arch. Intern. Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"499","DOI":"10.1016\/S0733-8651(18)30231-5","article-title":"Heart Rate Variability","volume":"10","author":"Monir","year":"1992","journal-title":"Cardiol. Clin."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"R927","DOI":"10.1152\/ajpregu.00452.2003","article-title":"Heart rate variability","volume":"285","author":"Stauss","year":"2003","journal-title":"Am. J. Physiol. Integr. Comp. Physiol."},{"key":"ref_29","unstructured":"(2007). Non-Invasive Sphygmomanometers\u2014Part 1: Requirements and Test Methods for Non-Automated Measurement Type (Standard No. ISO 81060-1:2007). Available online: https:\/\/www.iso.org\/standard\/42914.html."},{"key":"ref_30","unstructured":"(2018). Medical Electrical Equipment\u2014Part 2\u201330: Particular Requirements for Basic Safety and Essential Performance of Automated Non-Invasive Sphygmomanometers (Standard No. IEC 80601-2-30:2018). Available online: https:\/\/www.iso.org\/standard\/70653.html."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1931","DOI":"10.1097\/01.hjh.0000244940.11675.82","article-title":"Lack of sphygmomanometer calibration causes over- and under-detection of hypertension: A computer simulation study","volume":"24","author":"Turner","year":"2006","journal-title":"J. Hypertens."},{"key":"ref_32","unstructured":"(2023, July 20). About A Digital RF-Condenser Microphone, Paper 6130, 2004. Available online: http:\/\/www.aes.org\/e-lib\/browse.cfm?elib=12648."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1221","DOI":"10.1007\/s11517-009-0532-2","article-title":"A procedure for evaluation of non-invasive blood pressure simulators","volume":"47","author":"Gersak","year":"2009","journal-title":"Med. Biol. Eng. Comput."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"100260","DOI":"10.1016\/j.measen.2021.100260","article-title":"Physiology-based patient simulator for blood pressure meter testing","volume":"18","author":"Schiebl","year":"2021","journal-title":"Meas. Sensors"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1260\/026309209790252536","article-title":"Low Frequency Calibration of Measurement Microphones","volume":"28","author":"Rasmussen","year":"2009","journal-title":"J. Low Freq. Noise Vib. Act. Control"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"969","DOI":"10.1121\/1.414625","article-title":"The influence of microphone vents on measurements of acoustic intensity and impedance","volume":"99","author":"Li","year":"1996","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_37","unstructured":"Br\u00fcel&Kj\u00e6r (2023, July 20). Technical Documentation, Microphone Handbook Volume 1: Theory. March 2019. Available online: https:\/\/www.bksv.com\/media\/doc\/be1447.pdf."},{"key":"ref_38","unstructured":"(2023, August 04). G.R.A.S Low-Frequency Calibrator Type 42AE. Available online: https:\/\/www.grasacoustics.com\/files\/p\/d\/pd_42ae_ver_19_03_2008.pdf."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Choi, J., Kang, Y., Park, J., Joung, Y., and Koo, C. (2023). Development of Real-Time Cuffless Blood Pressure Measurement Systems with ECG Electrodes and a Microphone Using Pulse Transit Time (PTT). Sensors, 23.","DOI":"10.3390\/s23031684"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1051\/ijmqe\/2013045","article-title":"Acoustic metrology\u2013an overview of calibration methods and their uncertainties","volume":"4","author":"Frederiksen","year":"2013","journal-title":"Int. J. Metrol. Qual. Eng."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/19\/8340\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T21:03:44Z","timestamp":1760130224000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/19\/8340"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,10,9]]},"references-count":40,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2023,10]]}},"alternative-id":["s23198340"],"URL":"https:\/\/doi.org\/10.3390\/s23198340","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,10,9]]}}}