Red Blood Cells’ Area Deformation as the Origin of the Photoplethysmography Signal
The origin of the photoplethysmography (PPG) signal is a debatable topic, despite plausible models being addressed. One concern revolves around the correlation between the mechanical waveform’s pulsatile nature and the associated biomechanism. The interface between these domains requires a clear mat...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-11-01
|
| Series: | Sensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1424-8220/23/23/9515 |
| _version_ | 1797399599397208064 |
|---|---|
| author | Lucian Evdochim Eugen Chiriac Marioara Avram Lidia Dobrescu Dragoș Dobrescu Silviu Stanciu Stela Halichidis |
| author_facet | Lucian Evdochim Eugen Chiriac Marioara Avram Lidia Dobrescu Dragoș Dobrescu Silviu Stanciu Stela Halichidis |
| author_sort | Lucian Evdochim |
| collection | DOAJ |
| description | The origin of the photoplethysmography (PPG) signal is a debatable topic, despite plausible models being addressed. One concern revolves around the correlation between the mechanical waveform’s pulsatile nature and the associated biomechanism. The interface between these domains requires a clear mathematical or physical model that can explain physiological behavior. Describing the correct origin of the recorded optical waveform not only benefits the development of the next generation of biosensors but also defines novel health markers. In this study, the assumption of a pulsatile nature is based on the mechanism of blood microcirculation. At this level, two interconnected phenomena occur: variation in blood flow velocity through the capillary network and red blood cell (RBC) shape deformation. The latter effect was qualitatively investigated in synthetic capillaries to assess the experimental data needed for PPG model development. Erythrocytes passed through 10 µm and 6 µm microchannel widths with imposed velocities between 50 µm/s and 2000 µm/s, according to real scenarios. As a result, the length and area deformation of RBCs followed a logarithmic law function of the achieved traveling speeds. Applying radiometric expertise on top, mechanical-optical insights are obtained regarding PPG’s pulsatile nature. The mathematical equations derived from experimental data correlate microcirculation physiologic with waveform behavior at a high confidence level. The transfer function between the biomechanics and the optical signal is primarily influenced by the vasomotor state, capillary network orientation, concentration, and deformation performance of erythrocytes. |
| first_indexed | 2024-03-09T01:42:29Z |
| format | Article |
| id | doaj.art-d3d7c46c2459488b9f926552657dbe49 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-09T01:42:29Z |
| publishDate | 2023-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-d3d7c46c2459488b9f926552657dbe492023-12-08T15:26:16ZengMDPI AGSensors1424-82202023-11-012323951510.3390/s23239515Red Blood Cells’ Area Deformation as the Origin of the Photoplethysmography SignalLucian Evdochim0Eugen Chiriac1Marioara Avram2Lidia Dobrescu3Dragoș Dobrescu4Silviu Stanciu5Stela Halichidis6Department of Electronic Devices, Circuits, and Architectures, Faculty of Electronics, Telecommunications and Information Technology, University Politehnica of Bucharest, 060042 Bucharest, RomaniaNational Institute for Research and Development in Microtechnologies—IMT Bucharest, 077190 Voluntari, RomaniaNational Institute for Research and Development in Microtechnologies—IMT Bucharest, 077190 Voluntari, RomaniaDepartment of Electronic Devices, Circuits, and Architectures, Faculty of Electronics, Telecommunications and Information Technology, University Politehnica of Bucharest, 060042 Bucharest, RomaniaDepartment of Electronic Devices, Circuits, and Architectures, Faculty of Electronics, Telecommunications and Information Technology, University Politehnica of Bucharest, 060042 Bucharest, RomaniaLaboratory of Cardiovascular Noninvasive Investigations, Dr. Carol Davila Central Military Emergency University Hospital, 010242 Bucharest, RomaniaDepartment of Clinical Medical Disciplines, Faculty of Medicine, Ovidius University of Constanta, 900527 Constanta, RomaniaThe origin of the photoplethysmography (PPG) signal is a debatable topic, despite plausible models being addressed. One concern revolves around the correlation between the mechanical waveform’s pulsatile nature and the associated biomechanism. The interface between these domains requires a clear mathematical or physical model that can explain physiological behavior. Describing the correct origin of the recorded optical waveform not only benefits the development of the next generation of biosensors but also defines novel health markers. In this study, the assumption of a pulsatile nature is based on the mechanism of blood microcirculation. At this level, two interconnected phenomena occur: variation in blood flow velocity through the capillary network and red blood cell (RBC) shape deformation. The latter effect was qualitatively investigated in synthetic capillaries to assess the experimental data needed for PPG model development. Erythrocytes passed through 10 µm and 6 µm microchannel widths with imposed velocities between 50 µm/s and 2000 µm/s, according to real scenarios. As a result, the length and area deformation of RBCs followed a logarithmic law function of the achieved traveling speeds. Applying radiometric expertise on top, mechanical-optical insights are obtained regarding PPG’s pulsatile nature. The mathematical equations derived from experimental data correlate microcirculation physiologic with waveform behavior at a high confidence level. The transfer function between the biomechanics and the optical signal is primarily influenced by the vasomotor state, capillary network orientation, concentration, and deformation performance of erythrocytes.https://www.mdpi.com/1424-8220/23/23/9515photoplethysmography originred blood cell shape deformationmathematical transfer functionmicrocirculationvasomotor activity |
| spellingShingle | Lucian Evdochim Eugen Chiriac Marioara Avram Lidia Dobrescu Dragoș Dobrescu Silviu Stanciu Stela Halichidis Red Blood Cells’ Area Deformation as the Origin of the Photoplethysmography Signal Sensors photoplethysmography origin red blood cell shape deformation mathematical transfer function microcirculation vasomotor activity |
| title | Red Blood Cells’ Area Deformation as the Origin of the Photoplethysmography Signal |
| title_full | Red Blood Cells’ Area Deformation as the Origin of the Photoplethysmography Signal |
| title_fullStr | Red Blood Cells’ Area Deformation as the Origin of the Photoplethysmography Signal |
| title_full_unstemmed | Red Blood Cells’ Area Deformation as the Origin of the Photoplethysmography Signal |
| title_short | Red Blood Cells’ Area Deformation as the Origin of the Photoplethysmography Signal |
| title_sort | red blood cells area deformation as the origin of the photoplethysmography signal |
| topic | photoplethysmography origin red blood cell shape deformation mathematical transfer function microcirculation vasomotor activity |
| url | https://www.mdpi.com/1424-8220/23/23/9515 |
| work_keys_str_mv | AT lucianevdochim redbloodcellsareadeformationastheoriginofthephotoplethysmographysignal AT eugenchiriac redbloodcellsareadeformationastheoriginofthephotoplethysmographysignal AT marioaraavram redbloodcellsareadeformationastheoriginofthephotoplethysmographysignal AT lidiadobrescu redbloodcellsareadeformationastheoriginofthephotoplethysmographysignal AT dragosdobrescu redbloodcellsareadeformationastheoriginofthephotoplethysmographysignal AT silviustanciu redbloodcellsareadeformationastheoriginofthephotoplethysmographysignal AT stelahalichidis redbloodcellsareadeformationastheoriginofthephotoplethysmographysignal |