{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T16:23:13Z","timestamp":1783700593173,"version":"3.55.0"},"reference-count":46,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2019,4,28]],"date-time":"2019-04-28T00:00:00Z","timestamp":1556409600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["2018R1C1B5085702"],"award-info":[{"award-number":["2018R1C1B5085702"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002462","name":"Chungnam National University","doi-asserted-by":"publisher","award":["2018-1602-01"],"award-info":[{"award-number":["2018-1602-01"]}],"id":[{"id":"10.13039\/501100002462","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Suffering from continuous stress can lead to serious psychological and even physical disorders. Objective stress assessment methods using noninvasive physiological responses such as heart rate variability (HRV) and electroencephalograms (EEG) have therefore been proposed for effective stress management. In this study, a novel wearable device that can measure electrocardiograms (ECG) and EEG simultaneously was designed to enable continuous stress monitoring in daily life. The developed system is easily worn by hanging from both ears, is lightweight (i.e., 42.5 g), and exhibits an excellent noise performance of 0.12 \u03bcVrms. Significant time and frequency features of HRV and EEG were found in two different stressors, namely the Stroop color word and mental arithmetic tests, using 14 young subjects. Stressor situations were classified using various HRV and EEG feature selections and a support vector machine technique. The five-fold cross-validation results obtained when using both EEG and HRV features showed the best performance with an accuracy of 87.5%, which demonstrated the requirement for simultaneous HRV and EEG measurements.<\/jats:p>","DOI":"10.3390\/s19091991","type":"journal-article","created":{"date-parts":[[2019,4,29]],"date-time":"2019-04-29T02:57:32Z","timestamp":1556506652000},"page":"1991","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":176,"title":["A Novel Wearable EEG and ECG Recording System for Stress Assessment"],"prefix":"10.3390","volume":"19","author":[{"given":"Joong Woo","family":"Ahn","sequence":"first","affiliation":[{"name":"Seoul National University Hospital Biomedical Research Institute, Seoul 03082, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2737-4427","authenticated-orcid":false,"given":"Yunseo","family":"Ku","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, College of Medicine, Chungnam National University, Daejeon 35015, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2112-426X","authenticated-orcid":false,"given":"Hee Chan","family":"Kim","sequence":"additional","affiliation":[{"name":"Interdisciplinary Program in Bioengineering, Graduate School, Seoul National University, Seoul 03080, Korea"},{"name":"Department of Biomedical Engineering, College of Medicine, Seoul National University, Seoul 03080, Korea"},{"name":"Institute of Medical &amp; Biological Engineering, Medical Research Center, Seoul National University, Seoul 03080, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,4,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1016\/j.ijpsycho.2011.09.002","article-title":"The interactive effect of change in perceived stress and trait anxiety on vagal recovery from cognitive challenge","volume":"82","author":"Crowley","year":"2011","journal-title":"Int. J. Psychophysiol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"577","DOI":"10.1080\/02699930500270913","article-title":"Enhanced performance on executive functions associated with examination stress: Evidence from task-switching and Stroop paradigms","volume":"20","author":"Kofman","year":"2006","journal-title":"Cogn. Emot."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"601","DOI":"10.1037\/0033-2909.130.4.601","article-title":"Psychological stress and the human immune system: A meta-analytic study of 30 years of inquiry","volume":"130","author":"Segerstrom","year":"2004","journal-title":"Psychol. Bull."},{"key":"ref_4","unstructured":"(2019, April 27). Steven Sauter, L.M.e.a. Stress at Work. (NIOSH), T.N.I.f.O.S.a.H., Ed. NIOSH, Available online: https:\/\/www.cdc.gov\/niosh\/docs\/99-101\/default.html."},{"key":"ref_5","unstructured":"Pierce, C.M. (1988). Stress in the workplace. Black Families in Crisis: The Middle Class, Brunner\/Mazel."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"738","DOI":"10.2307\/256662","article-title":"Occupational stress, social support, and the costs of health care","volume":"39","author":"Manning","year":"1996","journal-title":"Acad. Manage. J."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1287","DOI":"10.1016\/j.cmpb.2012.07.003","article-title":"Objective measures, sensors and computational techniques for stress recognition and classification: A survey","volume":"108","author":"Sharma","year":"2012","journal-title":"Comput. Methods Programs Biomed."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0165-1781(00)00195-5","article-title":"Autonomic dysregulation in panic disorder and in post-traumatic stress disorder: Application of power spectrum analysis of heart rate variability at rest and in response to recollection of trauma or panic attacks","volume":"96","author":"Cohen","year":"2000","journal-title":"Psychiatry Res."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"796","DOI":"10.1097\/00006842-200011000-00009","article-title":"Depressed mood is related to high-frequency heart rate variability during stressors","volume":"62","author":"Hughes","year":"2000","journal-title":"Psychosom. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1007\/s10558-007-9028-6","article-title":"A Noninvasive Parametric Evaluation of Stress Effects on Global Cardiovascular Function","volume":"7","author":"Pan","year":"2007","journal-title":"Cardiovasc. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1126\/science.6166045","article-title":"Power spectrum analysis of heart rate fluctuation: A quantitative probe of beat-to-beat cardiovascular control","volume":"213","author":"Akselrod","year":"1981","journal-title":"Science"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1159\/000258725","article-title":"Evaluation of stress systems by applying noninvasive methodologies: Measurements of neuroimmune biomarkers in the sweat, heart rate variability and salivary cortisol","volume":"17","author":"Marques","year":"2010","journal-title":"Neuroimmunomodulation"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1319","DOI":"10.1088\/0967-3334\/35\/7\/1319","article-title":"Complexity and time asymmetry of heart rate variability are altered in acute mental stress","volume":"35","author":"Visnovcova","year":"2014","journal-title":"Physiol. Meas."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"370","DOI":"10.1016\/j.bspc.2015.02.012","article-title":"Acute mental stress assessment via short term HRV analysis in healthy adults: A systematic review with meta-analysis","volume":"18","author":"Castaldo","year":"2015","journal-title":"Biomed. Signal Process. Control"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1497","DOI":"10.1007\/s00421-010-1776-0","article-title":"Instantaneous changes in heart rate regulation due to mental load in simulated office work","volume":"111","author":"Taelman","year":"2011","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1016\/j.ijpsycho.2009.03.002","article-title":"A longitudinal study in youth of heart rate variability at rest and in response to stress","volume":"73","author":"Li","year":"2009","journal-title":"Int. J. Psychophysiol."},{"key":"ref_17","first-page":"227","article-title":"Effects of anxiety due to mental stress on heart rate variability in healthy subjects","volume":"52","author":"Traina","year":"2011","journal-title":"Minerva Psichiatrica"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1016\/j.biopsycho.2009.11.008","article-title":"Trait and state positive affect and cardiovascular recovery from experimental academic stress","volume":"83","author":"Papousek","year":"2010","journal-title":"Biol. Psychol."},{"key":"ref_19","first-page":"63","article-title":"Short-term heart rate variability measures in students during examinations","volume":"22","author":"Tharion","year":"2009","journal-title":"Natl. Med. J. India"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Seo, S.-H., and Lee, J.-T. (2010). Stress and EEG. ICHIT, InTech. Available online: https:\/\/www.intechopen.com\/books\/convergence-and-hybrid-information-technologies\/stress-and-eeg.","DOI":"10.5772\/9651"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1351","DOI":"10.1088\/0967-3334\/36\/7\/1351","article-title":"Stress assessment based on EEG univariate features and functional connectivity measures","volume":"36","author":"Alonso","year":"2015","journal-title":"Physiol. Meas."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1007\/s13534-012-0065-8","article-title":"Mental workload and task engagement evaluation based on changes in electroencephalogram","volume":"2","author":"Rabbi","year":"2012","journal-title":"Biomed. Eng. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1037\/0033-2909.89.1.19","article-title":"Lateral brain function, emotion, and conceptualization","volume":"89","author":"Tucker","year":"1981","journal-title":"Psychol. Bull."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1080\/02699939308409180","article-title":"Cerebral asymmetry and emotion: Conceptual and methodological conundrums","volume":"7","author":"Davidson","year":"1993","journal-title":"Cogn. Emot."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"219","DOI":"10.1016\/j.biopsycho.2004.03.008","article-title":"What does the prefrontal cortex \u201cdo\u201d in affect: Perspectives on frontal EEG asymmetry research","volume":"67","author":"Davidson","year":"2004","journal-title":"Biol. Psychol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1016\/j.biopsycho.2007.03.004","article-title":"The effect of a naturalistic stressor on frontal EEG asymmetry, stress, and health","volume":"75","author":"Lewis","year":"2007","journal-title":"Biol. Psychol."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Sulaiman, N., Mohd Nasir, T., Siti Armiza Mohd, A., Noor Hayatee Abdul, H., Lias, S., and Zunairah Haji, M. (December, January 30). Stress features identification from EEG signals using EEG Asymmetry & Spectral Centroids techniques. Proceedings of the 2010 IEEE EMBS Conference on Biomedical Engineering and Sciences (IECBES), Kuala Lumpur, Malaysia.","DOI":"10.1109\/IECBES.2010.5742273"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Hou, X., Liu, Y., Sourina, O., Tan, Y.R.E., Wang, L., and Mueller-Wittig, W. (2015, January 9\u201312). EEG Based Stress Monitoring. Proceedings of the 2015 IEEE International Conference on Systems, Man, and Cybernetics, Kowloon, China.","DOI":"10.1109\/SMC.2015.540"},{"key":"ref_29","unstructured":"Lin, T., and John, L. (2006, January 26\u201329). Quantifying Mental Relaxation with EEG for use in Computer Games. Proceedings of the International conference on internet computing, Las Vegas, NV, USA."},{"key":"ref_30","unstructured":"Dharmawan, Z. (2007). Analysis of Computer Games Player Stress Level Using EEG Data. [Master of Science Thesis Report, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology]."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Roh, T., Hong, S., Cho, H., and Yoo, H.-J. (2012, January 19\u201323). A 259.6 \u03bcW nonlinear HRV-EEG chaos processor with body channel communication interface for mental health monitoring. Proceedings of the Solid-State Circuits Conference Digest of Technical Papers (ISSCC), San Francisco, CA, USA.","DOI":"10.1109\/ISSCC.2012.6177020"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1109\/MPUL.2012.2216717","article-title":"The in-the-ear recording concept: User-centered and wearable brain monitoring","volume":"3","author":"Looney","year":"2012","journal-title":"IEEE Pulse"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"163","DOI":"10.3389\/fnhum.2017.00163","article-title":"Concealed, Unobtrusive Ear-Centered EEG Acquisition: cEEGrids for Transparent EEG","volume":"11","author":"Bleichner","year":"2017","journal-title":"Front. Hum. Neurosci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.ijpsycho.2012.01.009","article-title":"The time course of autonomic parameters and muscle tension during recovery following a moderate cognitive stressor: Dependency on trait anxiety level","volume":"84","author":"Willmann","year":"2012","journal-title":"Int. J. Psychophysiol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/j.physbeh.2004.03.031","article-title":"The anxiogenic video-recorded Stroop Color\u2013Word Test: Psychological and physiological alterations and effects of diazepam","volume":"82","author":"Prado","year":"2004","journal-title":"Physiol. Behav."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"829","DOI":"10.1038\/sj.jhh.1001624","article-title":"Cardiovascular haemodynamic response to repeated mental stress in normotensive subjects at genetic risk of hypertension: Evidence of enhanced reactivity, blunted adaptation, and delayed recovery","volume":"17","author":"Schneider","year":"2003","journal-title":"J. Hum. Hypertens."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Bansal, D., Khan, M., and Salhan, A.K. (2009, January 8\u201310). A Review of Measurement and Analysis of Heart Rate Variability. Proceedings of the 2009 International Conference on Computer and Automation Engineering, Bangkok, Thailand.","DOI":"10.1109\/ICCAE.2009.70"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"354","DOI":"10.1093\/oxfordjournals.eurheartj.a014868","article-title":"Heart rate variability: Standards of measurement, physiological interpretation, and clinical use","volume":"17","author":"Camm","year":"1996","journal-title":"Eur. Heart J."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1109\/TBME.1985.325532","article-title":"A real-time QRS detection algorithm","volume":"32","author":"Pan","year":"1985","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"502","DOI":"10.1109\/TSMCA.2008.918624","article-title":"Toward emotion recognition in car-racing drivers: A biosignal processing approach","volume":"38","author":"Katsis","year":"2008","journal-title":"IEEE Trans. Syst. Man Cybern. Part A Syst. Hum."},{"key":"ref_41","unstructured":"Zhai, J., and Barreto, A. (2006, January 11\u201313). Stress Recognition Using Non-invasive Technology. Proceedings of the FLAIRS Conference, Melbourne Beach, FL, USA."},{"key":"ref_42","first-page":"8","article-title":"Partitioning and layout of a mixed-signal PCB","volume":"18","author":"Ott","year":"2001","journal-title":"Print. Circuit Des."},{"key":"ref_43","unstructured":"Task Force of the European Society of Cardiology the North American Society of Pacing Electrophysiology (1996). Heart Rate Variability. Circulation, 93, 1043\u20131065."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1007\/s00421-004-1055-z","article-title":"The effect of mental stress on heart rate variability and blood pressure during computer work","volume":"92","author":"Hjortskov","year":"2004","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Hosseini, S.A., and Khalilzadeh, M.A. (2010, January 23\u201325). Emotional Stress Recognition System Using EEG and Psychophysiological Signals: Using New Labelling Process of EEG Signals in Emotional Stress State. Proceedings of the International Conference on Biomedical Engineering and Computer Science, Wuhan, China.","DOI":"10.1109\/ICBECS.2010.5462520"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"279","DOI":"10.1109\/TITB.2011.2169804","article-title":"Development and evaluation of an ambulatory stress monitor based on wearable sensors","volume":"16","author":"Choi","year":"2012","journal-title":"IEEE Trans. Inf. Technol. Biomed."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/9\/1991\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:47:47Z","timestamp":1760186867000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/9\/1991"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,4,28]]},"references-count":46,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2019,5]]}},"alternative-id":["s19091991"],"URL":"https:\/\/doi.org\/10.3390\/s19091991","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,4,28]]}}}