{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T16:12:16Z","timestamp":1776183136378,"version":"3.50.1"},"reference-count":22,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2021,11,14]],"date-time":"2021-11-14T00:00:00Z","timestamp":1636848000000},"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>We investigated the effects of a quality screening method on unconstrained measured signals, including electrocardiogram (ECG), photoplethysmogram (PPG), and ballistocardiogram (BCG) signals, in our collective chair system for smart healthcare. Such an investigation is necessary because unattached or unbound sensors have weaker connections to body parts than do conventional methods. Using the biosignal chair, the physiological signals collected during sessions included a virtual driving task, a physically powered wheelchair drive, and three types of body motions. The signal quality index was defined by the similarity between the observed signals and noise-free signals from the perspective of the cross-correlations of coefficients with appropriate individual templates. The goal of the index was to qualify signals without a reference signal to assess the practical use of the chair in daily life. As expected, motion artifacts have adverse effects on the stability of physiological signals. However, we were able to observe a supplementary relationship between sensors depending on each movement trait. Except for extreme movements, the signal quality and estimated heart rate (HR) remained within the range of criteria usable for status monitoring. By investigating the signal reliability, we were able to confirm the suitability of using the unconstrained biosignal chair to collect real-life measurements to improve safety and healthcare.<\/jats:p>","DOI":"10.3390\/s21227564","type":"journal-article","created":{"date-parts":[[2021,11,14]],"date-time":"2021-11-14T20:51:53Z","timestamp":1636923113000},"page":"7564","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Signal Quality Index Based on Template Cross-Correlation in Multimodal Biosignal Chair for Smart Healthcare"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4242-7638","authenticated-orcid":false,"given":"Seunghyeok","family":"Hong","sequence":"first","affiliation":[{"name":"Division of Data Science, The University of Suwon, Wauan-gil 17, Hwaseong-si 18562, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jeong","family":"Heo","sequence":"additional","affiliation":[{"name":"LG Electronics CTO Division Future Technology Center A.I. Lab., Seoul 06763, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kwang Suk","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, College of Medicine, Seoul National University, Seoul 03080, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,11,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.ins.2018.04.003","article-title":"Intelligent system for drowsiness recognition based on ear canal electroencephalography with photoplethysmography and electrocardiography","volume":"453","author":"Hong","year":"2018","journal-title":"Inf. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/TSMCC.2009.2032660","article-title":"A survey on wearable sensor-based systems for health monitoring and prognosis","volume":"40","author":"Pantelopoulos","year":"2009","journal-title":"IEEE Trans. Syst. Man Cybern. Part C Appl. Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1109\/MSP.2016.2602095","article-title":"Driver Status Monitoring Systems for Smart Vehicles Using Physiological Sensors: A safety enhancement system from automobile manufacturers","volume":"33","author":"Choi","year":"2016","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"956","DOI":"10.1109\/TBME.2006.872823","article-title":"ECG measurement on a chair without conductive contact","volume":"53","author":"Lim","year":"2006","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"6698567","DOI":"10.1155\/2021\/6698567","article-title":"Noncontact ECG Monitoring by Capacitive Coupling of Textiles in a Chair","volume":"2021","author":"Su","year":"2021","journal-title":"J. Healthc. Eng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1085","DOI":"10.1109\/TITB.2009.2031108","article-title":"Photoplethysmogram measurement without direct skin-to-sensor contact using an adaptive light source intensity control","volume":"13","author":"Baek","year":"2009","journal-title":"IEEE Trans. Inf. Technol. Biomed."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"150","DOI":"10.1109\/TITB.2011.2175742","article-title":"A smart health monitoring chair for nonintrusive measurement of biological signals","volume":"16","author":"Baek","year":"2012","journal-title":"IEEE Trans. Inf. Technol. Biomed."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Wang, J., Warnecke, J.M., Haghi, M., and Deserno, T.M. (2020). Unobtrusive health monitoring in private spaces: The smart vehicle. Sensors, 20.","DOI":"10.3390\/s20092442"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2832","DOI":"10.1109\/JSEN.2016.2519392","article-title":"Capacitive Biopotential Measurement for Electrophysiological Signal Acquisition: A Review","volume":"16","author":"Sun","year":"2016","journal-title":"IEEE Sens. J."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1399","DOI":"10.1088\/0967-3334\/36\/7\/1399","article-title":"Polyvinylidene fluoride sensor-based method for unconstrained snoring detection","volume":"36","author":"Hwang","year":"2015","journal-title":"Physiol. Meas."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1154","DOI":"10.1016\/j.medengphy.2009.07.020","article-title":"Ballistocardiogaphic studies with acceleration and electromechanical film sensors","volume":"31","author":"Viik","year":"2009","journal-title":"Med. Eng. Phys."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Lee, W.K., Yoon, H., Han, C., Joo, K.M., and Park, K.S. (2016). Physiological signal monitoring bed for infants based on load-cell sensors. Sensors, 16.","DOI":"10.3390\/s16030409"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"739","DOI":"10.2478\/v10178-012-0065-0","article-title":"Study on ballistocardiogram acquisition in a moving wheelchair with embedded sensors","volume":"19","author":"Pinheiro","year":"2012","journal-title":"Metrol. Meas. Syst."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"718","DOI":"10.1109\/TBME.2006.889194","article-title":"ECG Recording on a Bed During Sleep Without Direct Skin-Contact","volume":"54","author":"Lim","year":"2007","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"3606","DOI":"10.1109\/JBHI.2020.2979168","article-title":"Long Short-Term Memory Networks for Unconstrained Sleep Stage Classification Using Polyvinylidene Fluoride Film Sensor","volume":"24","author":"Choi","year":"2020","journal-title":"IEEE J. Biomed. Health Inform."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Hoog Antink, C., Schulz, F., Leonhardt, S., and Walter, M. (2018). Motion Artifact Quantification and Sensor Fusion for Unobtrusive Health Monitoring. Sensors, 18.","DOI":"10.3390\/s18010038"},{"key":"ref_17","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_18","doi-asserted-by":"crossref","unstructured":"Shin, J.H., Choi, B.H., Lim, Y.G., Jeong, D.U., and Park, K.S. (2008, January 20\u201325). Automatic ballistocardiogram (BCG) beat detection using a template matching approach. Proceedings of the 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vancouver, BC, Canada.","DOI":"10.1109\/IEMBS.2008.4649363"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1177\/096228029900800204","article-title":"Measuring agreement in method comparison studies","volume":"8","author":"Bland","year":"1999","journal-title":"Stat. Methods Med. Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3112","DOI":"10.1109\/TBME.2011.2163715","article-title":"ECG on the road: Robust and unobtrusive estimation of heart rate","volume":"58","author":"Wartzek","year":"2011","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"722","DOI":"10.1109\/JBHI.2017.2686436","article-title":"Automated ECG noise detection and classification system for unsupervised healthcare monitoring","volume":"22","author":"Satija","year":"2018","journal-title":"IEEE J. Biomed. Health Inform."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1216","DOI":"10.1109\/JBHI.2016.2615316","article-title":"Quality Assessment of Ambulatory ECG Using Wavelet Entropy of the HRV Signal","volume":"21","author":"Orphanidou","year":"2017","journal-title":"IEEE J. Biomed. Health Inform."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/22\/7564\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:30:00Z","timestamp":1760167800000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/22\/7564"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,11,14]]},"references-count":22,"journal-issue":{"issue":"22","published-online":{"date-parts":[[2021,11]]}},"alternative-id":["s21227564"],"URL":"https:\/\/doi.org\/10.3390\/s21227564","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,11,14]]}}}