Accuracy of the Instantaneous Breathing and Heart Rates Estimated by Smartphone Inertial Units
Seismocardiography (SCG) and Gyrocardiography (GCG) use lightweight, miniaturized accelerometers and gyroscopes to record, respectively, cardiac-induced linear accelerations and angular velocities of the chest wall. These inertial sensors are also sensitive to thoracic movements with respiration, wh...
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MDPI AG
2025-02-01
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| Online Access: | https://www.mdpi.com/1424-8220/25/4/1094 |
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| author | Eliana Cinotti Jessica Centracchio Salvatore Parlato Daniele Esposito Antonio Fratini Paolo Bifulco Emilio Andreozzi |
| author_facet | Eliana Cinotti Jessica Centracchio Salvatore Parlato Daniele Esposito Antonio Fratini Paolo Bifulco Emilio Andreozzi |
| author_sort | Eliana Cinotti |
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| description | Seismocardiography (SCG) and Gyrocardiography (GCG) use lightweight, miniaturized accelerometers and gyroscopes to record, respectively, cardiac-induced linear accelerations and angular velocities of the chest wall. These inertial sensors are also sensitive to thoracic movements with respiration, which cause baseline wanderings in SCG and GCG signals. Nowadays, accelerometers and gyroscopes are widely integrated into smartphones, thus increasing the potential of SCG and GCG as cardiorespiratory monitoring tools. This study investigates the accuracy of smartphone inertial sensors in simultaneously measuring instantaneous heart rates and breathing rates. Smartphone-derived SCG and GCG signals were acquired from 10 healthy subjects at rest. The performances of heartbeats and respiratory acts detection, as well as of inter-beat intervals (IBIs) and inter-breath intervals (IBrIs) estimation, were evaluated for both SCG and GCG via the comparison with simultaneous electrocardiography and respiration belt signals. Heartbeats were detected with a sensitivity and positive predictive value (PPV) of 89.3% and 93.3% in SCG signals and of 97.3% and 97.9% in GCG signals. Moreover, IBIs measurements reported strong linear relationships (R<sup>2</sup> > 0.999), non-significant biases, and Bland–Altman limits of agreement (LoA) of ±7.33 ms for SCG and ±5.22 ms for GCG. On the other hand, respiratory acts detection scored a sensitivity and PPV of 95.6% and 94.7% for SCG and of 95.7% and 92.0% for GCG. Furthermore, high R<sup>2</sup> values (0.976 and 0.968, respectively), non-significant biases, and an LoA of ±0.558 s for SCG and ±0.749 s for GCG were achieved for IBrIs estimates. The results of this study confirm that smartphone inertial sensors can provide accurate measurements of both instantaneous heart rate and breathing rate without the need for additional devices. |
| format | Article |
| id | doaj-art-69a76d01586247d79ffaa80b19bcc6d9 |
| institution | OA Journals |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | MDPI AG |
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| series | Sensors |
| spelling | doaj-art-69a76d01586247d79ffaa80b19bcc6d92025-08-20T02:01:24ZengMDPI AGSensors1424-82202025-02-01254109410.3390/s25041094Accuracy of the Instantaneous Breathing and Heart Rates Estimated by Smartphone Inertial UnitsEliana Cinotti0Jessica Centracchio1Salvatore Parlato2Daniele Esposito3Antonio Fratini4Paolo Bifulco5Emilio Andreozzi6Department of Electrical Engineering and Information Technologies, University of Naples Federico II, Via Claudio, 21, I-80125 Naples, ItalyDepartment of Electrical Engineering and Information Technologies, University of Naples Federico II, Via Claudio, 21, I-80125 Naples, ItalyDepartment of Electrical Engineering and Information Technologies, University of Naples Federico II, Via Claudio, 21, I-80125 Naples, ItalyDepartment of Information and Electrical Engineering and Applied Mathematics, University of Salerno, Via Giovanni Paolo II, 132, I-84084 Fisciano, ItalyCollege of Engineering and Physical Sciences, Aston University, Birmingham B4 7ET, UKDepartment of Electrical Engineering and Information Technologies, University of Naples Federico II, Via Claudio, 21, I-80125 Naples, ItalyDepartment of Electrical Engineering and Information Technologies, University of Naples Federico II, Via Claudio, 21, I-80125 Naples, ItalySeismocardiography (SCG) and Gyrocardiography (GCG) use lightweight, miniaturized accelerometers and gyroscopes to record, respectively, cardiac-induced linear accelerations and angular velocities of the chest wall. These inertial sensors are also sensitive to thoracic movements with respiration, which cause baseline wanderings in SCG and GCG signals. Nowadays, accelerometers and gyroscopes are widely integrated into smartphones, thus increasing the potential of SCG and GCG as cardiorespiratory monitoring tools. This study investigates the accuracy of smartphone inertial sensors in simultaneously measuring instantaneous heart rates and breathing rates. Smartphone-derived SCG and GCG signals were acquired from 10 healthy subjects at rest. The performances of heartbeats and respiratory acts detection, as well as of inter-beat intervals (IBIs) and inter-breath intervals (IBrIs) estimation, were evaluated for both SCG and GCG via the comparison with simultaneous electrocardiography and respiration belt signals. Heartbeats were detected with a sensitivity and positive predictive value (PPV) of 89.3% and 93.3% in SCG signals and of 97.3% and 97.9% in GCG signals. Moreover, IBIs measurements reported strong linear relationships (R<sup>2</sup> > 0.999), non-significant biases, and Bland–Altman limits of agreement (LoA) of ±7.33 ms for SCG and ±5.22 ms for GCG. On the other hand, respiratory acts detection scored a sensitivity and PPV of 95.6% and 94.7% for SCG and of 95.7% and 92.0% for GCG. Furthermore, high R<sup>2</sup> values (0.976 and 0.968, respectively), non-significant biases, and an LoA of ±0.558 s for SCG and ±0.749 s for GCG were achieved for IBrIs estimates. The results of this study confirm that smartphone inertial sensors can provide accurate measurements of both instantaneous heart rate and breathing rate without the need for additional devices.https://www.mdpi.com/1424-8220/25/4/1094gyrocardiographyseismocardiographyheartbeat detectionrespirationheart ratebreathing rate |
| spellingShingle | Eliana Cinotti Jessica Centracchio Salvatore Parlato Daniele Esposito Antonio Fratini Paolo Bifulco Emilio Andreozzi Accuracy of the Instantaneous Breathing and Heart Rates Estimated by Smartphone Inertial Units Sensors gyrocardiography seismocardiography heartbeat detection respiration heart rate breathing rate |
| title | Accuracy of the Instantaneous Breathing and Heart Rates Estimated by Smartphone Inertial Units |
| title_full | Accuracy of the Instantaneous Breathing and Heart Rates Estimated by Smartphone Inertial Units |
| title_fullStr | Accuracy of the Instantaneous Breathing and Heart Rates Estimated by Smartphone Inertial Units |
| title_full_unstemmed | Accuracy of the Instantaneous Breathing and Heart Rates Estimated by Smartphone Inertial Units |
| title_short | Accuracy of the Instantaneous Breathing and Heart Rates Estimated by Smartphone Inertial Units |
| title_sort | accuracy of the instantaneous breathing and heart rates estimated by smartphone inertial units |
| topic | gyrocardiography seismocardiography heartbeat detection respiration heart rate breathing rate |
| url | https://www.mdpi.com/1424-8220/25/4/1094 |
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