Photoplethysmography (PPG) is a non-invasive method used for cardiovascular monitoring, with multi-wavelength PPG (MW-PPG) enhancing its efficacy by using multiple wavelengths for improved assessment. This study explores how contact force (CF) variations impact MW-PPG signals. Data from 11 healthy subjects are analyzed to investigate the still understudied specific effects of CF on PPG signals. The obtained dataset includes simultaneous recording of five PPG wavelengths (470, 525, 590, 631, and 940 nm), CF, skin temperature, and the tonometric measurement derived from CF. The evolution of raw signals and the PPG DC and AC components are analyzed in relation to the increasing and decreasing faces of the CF. Findings reveal individual variability in signal responses related to skin and vasculature properties and demonstrate hysteresis and wavelength-dependent responses to CF changes. Notably, all wavelengths except 631 nm showed that the DC component of PPG signals correlates with CF trends, suggesting the potential use of this component as an indirect CF indicator. However, further validation is needed for practical application. The study underscores the importance of biomechanical properties at the measurement site and inter-individual variability and proposes the arterial pressure wave as a key factor in PPG signal formation.
Lambert Cause, J, Sole Morillo, A, da Silva, B, Garcia-Naranjo, JC & Stiens, J 2024, 'Evaluating Vascular Depth-Dependent Changes in Multi-Wavelength PPG Signals Due to Contact Force', Sensors (Basel, Switzerland), vol. 24, no. 9, 2692. https://doi.org/10.3390/s24092692
Lambert Cause, J., Sole Morillo, A., da Silva, B., Garcia-Naranjo, J. C., & Stiens, J. (2024). Evaluating Vascular Depth-Dependent Changes in Multi-Wavelength PPG Signals Due to Contact Force. Sensors (Basel, Switzerland), 24(9), Article 2692. https://doi.org/10.3390/s24092692
@article{5e098c4a8fe149fc84b2f3655e50259a,
title = "Evaluating Vascular Depth-Dependent Changes in Multi-Wavelength PPG Signals Due to Contact Force",
abstract = "Photoplethysmography (PPG) is a non-invasive method used for cardiovascular monitoring, with multi-wavelength PPG (MW-PPG) enhancing its efficacy by using multiple wavelengths for improved assessment. This study explores how contact force (CF) variations impact MW-PPG signals. Data from 11 healthy subjects are analyzed to investigate the still understudied specific effects of CF on PPG signals. The obtained dataset includes simultaneous recording of five PPG wavelengths (470, 525, 590, 631, and 940 nm), CF, skin temperature, and the tonometric measurement derived from CF. The evolution of raw signals and the PPG DC and AC components are analyzed in relation to the increasing and decreasing faces of the CF. Findings reveal individual variability in signal responses related to skin and vasculature properties and demonstrate hysteresis and wavelength-dependent responses to CF changes. Notably, all wavelengths except 631 nm showed that the DC component of PPG signals correlates with CF trends, suggesting the potential use of this component as an indirect CF indicator. However, further validation is needed for practical application. The study underscores the importance of biomechanical properties at the measurement site and inter-individual variability and proposes the arterial pressure wave as a key factor in PPG signal formation.",
keywords = "photoplethysmography, multi-wavelength PPG, contact force, signal morphology, skin viscoelasticity",
author = "\{Lambert Cause\}, Joan and \{Sole Morillo\}, Angel and \{da Silva\}, Bruno and Garcia-Naranjo, \{Juan Carlos\} and Johan Stiens",
note = "Funding Information: We acknowledge VUB for the SRP (Strategic Research Program) LSDS and the IOF- GEAR TECH4HEALTH project funding and ETRO.RDI BAS funding. We also thank the Belgian Development Cooperation through VLIR-UOS (Flemish Interuniversity Council-University Cooperation for Development) in the context of the Institutional University Cooperation program (IUC 2019 Phase 2 UO) with the Universidad de Oriente (Cuba). This work has been partially supported by the FWO-Flanders FWOSB106 Ph.D. grant and partially by Innoviris-Brussels through the ILSF projects BRGEOZ403 and BRGEOZ422. Funding Information: We sincerely thank our volunteers, whose participation was crucial to our research. Appreciation is due the researchers at the Center for Medical Biophysics in Santiago de Cuba for enhancing our work and to Alexis Pich\textbackslash{}u00EDn Quezada and Alfredo Aldama Figueroa for their vital clinical guidance. We also acknowledge the funding from SRP (Strategic Research Program) LSDS and the IOF-GEAR TECH4HEALTH project, ETRO.RDI. Their collective support has been instrumental to advancing photoplethysmography. Publisher Copyright: {\textcopyright} 2024 by the authors.",
year = "2024",
month = apr,
day = "24",
doi = "10.3390/s24092692",
language = "English",
volume = "24",
journal = "Sensors (Basel, Switzerland)",
issn = "1424-8220",
publisher = "Multidisciplinary Digital Publishing Institute (MDPI)",
number = "9",
}