Experimental Analysis on the Effect of Contact Pressure and Activity Level as Influencing Factors in PPG Sensor Performance
Photoplethysmographic (PPG) sensors are small and cheap wearable sensors which open the possibility of monitoring physiological parameters such as heart rate during normal daily routines, ultimately providing valuable information on health status. Despite their potential and distribution within wear...
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MDPI AG
2025-07-01
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| author | Francesco Scardulla Gloria Cosoli Cosmina Gnoffo Luca Antognoli Francesco Bongiorno Gianluca Diana Lorenzo Scalise Leonardo D’Acquisto Marco Arnesano |
| author_facet | Francesco Scardulla Gloria Cosoli Cosmina Gnoffo Luca Antognoli Francesco Bongiorno Gianluca Diana Lorenzo Scalise Leonardo D’Acquisto Marco Arnesano |
| author_sort | Francesco Scardulla |
| collection | DOAJ |
| description | Photoplethysmographic (PPG) sensors are small and cheap wearable sensors which open the possibility of monitoring physiological parameters such as heart rate during normal daily routines, ultimately providing valuable information on health status. Despite their potential and distribution within wearable devices, their accuracy is affected by several influencing parameters, such as contact pressure and physical activity. In this study, the effect of contact pressure (i.e., at 20, 60, and 75 mmHg) and intensity of physical activity (i.e., at 3, 6, and 8 km/h) were evaluated on a sample of 25 subjects using both a reference device (i.e., an electrocardiography-based device) and a PPG sensor applied to the skin with controlled contact pressure values. Results showed differing accuracy and precision when measuring the heart rate at different pressure levels, achieving the best performance at a contact pressure of 60 mmHg, with a mean absolute percentage error of between 3.36% and 6.83% depending on the physical activity levels, and a Pearson’s correlation coefficient of between 0.81 and 0.95. Plus, considering the individual optimal contact pressure, measurement uncertainty significantly decreases at any contact pressure, for instance, decreasing from 15 bpm (at 60 mmHg) to 8 bpm when running at a speed of 6 km/h (coverage factor k = 2). These results may constitute useful information for both users and manufacturers to improve the metrological performance of PPG sensors and expand their use in a clinical context. |
| format | Article |
| id | doaj-art-e4f8a8624e4d4327a234bc8067bb1732 |
| institution | Kabale University |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
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| series | Sensors |
| spelling | doaj-art-e4f8a8624e4d4327a234bc8067bb17322025-08-20T03:32:18ZengMDPI AGSensors1424-82202025-07-012514447710.3390/s25144477Experimental Analysis on the Effect of Contact Pressure and Activity Level as Influencing Factors in PPG Sensor PerformanceFrancesco Scardulla0Gloria Cosoli1Cosmina Gnoffo2Luca Antognoli3Francesco Bongiorno4Gianluca Diana5Lorenzo Scalise6Leonardo D’Acquisto7Marco Arnesano8Department of Engineering, University of Palermo, Viale delle Scienze, Ed. 8, 90128 Palermo, ItalyDepartment of Theorethical and Applied Sciences, eCampus University, v. Isimbardi 10, 22060 Novedrate, ItalyDepartment of Engineering, University of Palermo, Viale delle Scienze, Ed. 8, 90128 Palermo, ItalyDepartment of Industrial Engineering and Mathematical Sciences, Marche Polytechnic University, v. Brecce Bianche 12, 60131 Ancona, ItalyDepartment of Engineering, University of Palermo, Viale delle Scienze, Ed. 8, 90128 Palermo, ItalyDepartment of Engineering, University of Palermo, Viale delle Scienze, Ed. 8, 90128 Palermo, ItalyDepartment of Industrial Engineering and Mathematical Sciences, Marche Polytechnic University, v. Brecce Bianche 12, 60131 Ancona, ItalyDepartment of Engineering, University of Palermo, Viale delle Scienze, Ed. 8, 90128 Palermo, ItalyDepartment of Theorethical and Applied Sciences, eCampus University, v. Isimbardi 10, 22060 Novedrate, ItalyPhotoplethysmographic (PPG) sensors are small and cheap wearable sensors which open the possibility of monitoring physiological parameters such as heart rate during normal daily routines, ultimately providing valuable information on health status. Despite their potential and distribution within wearable devices, their accuracy is affected by several influencing parameters, such as contact pressure and physical activity. In this study, the effect of contact pressure (i.e., at 20, 60, and 75 mmHg) and intensity of physical activity (i.e., at 3, 6, and 8 km/h) were evaluated on a sample of 25 subjects using both a reference device (i.e., an electrocardiography-based device) and a PPG sensor applied to the skin with controlled contact pressure values. Results showed differing accuracy and precision when measuring the heart rate at different pressure levels, achieving the best performance at a contact pressure of 60 mmHg, with a mean absolute percentage error of between 3.36% and 6.83% depending on the physical activity levels, and a Pearson’s correlation coefficient of between 0.81 and 0.95. Plus, considering the individual optimal contact pressure, measurement uncertainty significantly decreases at any contact pressure, for instance, decreasing from 15 bpm (at 60 mmHg) to 8 bpm when running at a speed of 6 km/h (coverage factor k = 2). These results may constitute useful information for both users and manufacturers to improve the metrological performance of PPG sensors and expand their use in a clinical context.https://www.mdpi.com/1424-8220/25/14/4477photoplethysmographyPPGPPG sensorcontact pressurecontact forceactivity level |
| spellingShingle | Francesco Scardulla Gloria Cosoli Cosmina Gnoffo Luca Antognoli Francesco Bongiorno Gianluca Diana Lorenzo Scalise Leonardo D’Acquisto Marco Arnesano Experimental Analysis on the Effect of Contact Pressure and Activity Level as Influencing Factors in PPG Sensor Performance Sensors photoplethysmography PPG PPG sensor contact pressure contact force activity level |
| title | Experimental Analysis on the Effect of Contact Pressure and Activity Level as Influencing Factors in PPG Sensor Performance |
| title_full | Experimental Analysis on the Effect of Contact Pressure and Activity Level as Influencing Factors in PPG Sensor Performance |
| title_fullStr | Experimental Analysis on the Effect of Contact Pressure and Activity Level as Influencing Factors in PPG Sensor Performance |
| title_full_unstemmed | Experimental Analysis on the Effect of Contact Pressure and Activity Level as Influencing Factors in PPG Sensor Performance |
| title_short | Experimental Analysis on the Effect of Contact Pressure and Activity Level as Influencing Factors in PPG Sensor Performance |
| title_sort | experimental analysis on the effect of contact pressure and activity level as influencing factors in ppg sensor performance |
| topic | photoplethysmography PPG PPG sensor contact pressure contact force activity level |
| url | https://www.mdpi.com/1424-8220/25/14/4477 |
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