{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,18]],"date-time":"2026-01-18T07:52:43Z","timestamp":1768722763179,"version":"3.49.0"},"reference-count":30,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2022,5,28]],"date-time":"2022-05-28T00:00:00Z","timestamp":1653696000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Junta de Andaluc\u00eda (Spain)","award":["PYC20-RE-040 UGR"],"award-info":[{"award-number":["PYC20-RE-040 UGR"]}]},{"name":"Junta de Andaluc\u00eda (Spain)","award":["PID2019-103938RB-I00"],"award-info":[{"award-number":["PID2019-103938RB-I00"]}]},{"name":"Spanish MCIN\/AEI\/10.13039\/501100011033\/","award":["PYC20-RE-040 UGR"],"award-info":[{"award-number":["PYC20-RE-040 UGR"]}]},{"name":"Spanish MCIN\/AEI\/10.13039\/501100011033\/","award":["PID2019-103938RB-I00"],"award-info":[{"award-number":["PID2019-103938RB-I00"]}]},{"name":"European Regional Development Funds (ERDF)","award":["PYC20-RE-040 UGR"],"award-info":[{"award-number":["PYC20-RE-040 UGR"]}]},{"name":"European Regional Development Funds (ERDF)","award":["PID2019-103938RB-I00"],"award-info":[{"award-number":["PID2019-103938RB-I00"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this work, we present a ballistocardiographic (BCG) system for the determination of heart and breath rates and activity of a user lying in bed. Our primary goal was to simplify the analog and digital processing usually required in these kinds of systems while retaining high performance. A novel sensing approach is proposed consisting of a white LED facing a digital light detector. This detector provides precise measurements of the variations of the light intensity of the incident light due to the vibrations of the bed produced by the subject\u2019s breathing, heartbeat, or activity. Four small springs, acting as a bandpass filter, connect the boards where the LED and the detector are mounted. Owing to the mechanical bandpass filtering caused by the compressed springs, the proposed system generates a BCG signal that reflects the main frequencies of the heartbeat, breathing, and movement of the lying subject. Without requiring any analog signal processing, this device continuously transmits the measurements to a microcontroller through a two-wire communication protocol, where they are processed to provide an estimation of the parameters of interest in configurable time intervals. The final information of interest is wirelessly sent to the user\u2019s smartphone by means of a Bluetooth connection. For evaluation purposes, the proposed system has been compared with typical BCG systems showing excellent performance for different subject positions. Moreover, applied postprocessing methods have shown good behavior for information separation from a single-channel signal. Therefore, the determination of the heart rate, breathing rate, and activity of the patient is achieved through a highly simplified signal processing without any need for analog signal conditioning.<\/jats:p>","DOI":"10.3390\/s22114112","type":"journal-article","created":{"date-parts":[[2022,5,31]],"date-time":"2022-05-31T02:30:06Z","timestamp":1653964206000},"page":"4112","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Digital Optical Ballistocardiographic System for Activity, Heart Rate, and Breath Rate Determination during Sleep"],"prefix":"10.3390","volume":"22","author":[{"given":"Nuria","family":"L\u00f3pez-Ruiz","sequence":"first","affiliation":[{"name":"ECsens, CITIC-UGR, Department of Electronics and Computer Technology, University of Granada, 18071 Granada, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1701-8878","authenticated-orcid":false,"given":"Pablo","family":"Escobedo","sequence":"additional","affiliation":[{"name":"ECsens, CITIC-UGR, Department of Electronics and Computer Technology, University of Granada, 18071 Granada, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2522-6108","authenticated-orcid":false,"given":"Isidoro","family":"Ruiz-Garc\u00eda","sequence":"additional","affiliation":[{"name":"ECsens, CITIC-UGR, Department of Electronics and Computer Technology, University of Granada, 18071 Granada, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0234-4758","authenticated-orcid":false,"given":"Miguel A.","family":"Carvajal","sequence":"additional","affiliation":[{"name":"ECsens, CITIC-UGR, Department of Electronics and Computer Technology, University of Granada, 18071 Granada, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9050-5413","authenticated-orcid":false,"given":"Alberto J.","family":"Palma","sequence":"additional","affiliation":[{"name":"ECsens, CITIC-UGR, Department of Electronics and Computer Technology, University of Granada, 18071 Granada, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6765-789X","authenticated-orcid":false,"given":"Antonio","family":"Mart\u00ednez-Olmos","sequence":"additional","affiliation":[{"name":"ECsens, CITIC-UGR, Department of Electronics and Computer Technology, University of Granada, 18071 Granada, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1152\/ajplegacy.1939.127.1.1","article-title":"Studies on the estimation of cardiac output in man, and of abnormalities in cardiac function, from the heart\u2019s recoil and the blood\u2019s impacts; the ballistocardiogram","volume":"127","author":"Starr","year":"1939","journal-title":"Am. 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