Effect of skin pigmentation and finger choice on accuracy of oxygen saturation measurement in an IoT-based pulse oximeter
Open accessAbstract
Pulse oximeters are widely used in hospitals and homes for measurement of blood oxygen saturation level (SpO2) and heart rate (HR). Concern has been raised regarding a possible bias in obtaining pulse oximeter measurements from different fingertips and the potential effect of skin pigmentation (white, brown, and dark). In this study, we obtained 600 SpO2 measurements from 20 volunteers using three UK NHS-approved commercial pulse oximeters alongside our custom-developed sensor, and used the Munsell colour system (5YR and 7.5YR cards) to classify the participants’ skin pigmentation into three distinct categories (white, brown, and dark). The statistical analysis using ANOVA post hoc tests (Bonferroni correction), a Bland–Altman plot, and a correlation test were then carried out to determine if there was clinical significance in measuring the SpO2 from different fingertips and to highlight if skin pigmentation affects the accuracy of SpO2 measurement. The results indicate that although the three commercial pulse oximeters had different means and standard deviations, these differences had no clinical significance.
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Red and infrared light wavelengths, which are less absorbed by melanin, have potential to reduce error rates and enhance inclusivity.
“Additionally, Dias et al. (2018) and Castaneda et al. (2018) highlighted the potential of red and infrared light wavelengths, which are less absorbed by melanin, to reduce error rates and enhance inclusivity [16,17].”
From Photoplethysmography in Diverse Skin Tones: Evaluating Bias in Smartwatch Health Monitoring (2025) · cites this paper as [16]
Section 3.1 says red and near-infrared light penetrate biological tissue more deeply than several other wavelengths and are used in pulse oximeters. It does not say they are less absorbed by melanin or that using them reduces pigmentation-related errors or enhances inclusivity; Section 5.2 reports no significant difference between the skin-colour groups tested, not a wavelength-based improvement. (LLM, conf=0.82)
Experimental — accuracy not yet measuredHeart rate variability applications showed promise but remain underexplored in terms of pigmentation differences.
“On the other hand, heart rate variability (HRV) applications showed promise but remain underexplored in terms of pigmentation differences [16].”
From Photoplethysmography in Diverse Skin Tones: Evaluating Bias in Smartwatch Health Monitoring (2025) · cites this paper as [16]
The Abstract describes measurements of oxygen saturation (SpO2) and heart rate, while Results and Discussion §5.2 compares SpO2 readings across skin colours. A search for “heart rate variability” and HRV applications found no passage assessing their promise or whether pigmentation differences remain underexplored. (LLM, conf=0.76)
Experimental — accuracy not yet measured
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- Authors
- Haxha, S., Nwibor, C., Ali, M., Sakel, M., Saunders, K., Dyo, V., & Nabakooza, S.
- Affiliations
- Royal Holloway University of London (GB)
- East Kent Hospitals University NHS Foundation Trust (GB)
- Hertfordshire Partnership University NHS Foundation Trust (GB)
- Corresponding author
- Haxha, Shyqyri
- Venue
- Sensors
- Publisher
- MDPI AG
- Published
- 2024-05-22
- Volume
- 24
- Issue
- 11
- Pages
- 3301
- ISSN
- 1424-8220 (ISSN-L)
- PMC
- PMC11174708
- OpenAlex
- W4398206902
- Cited by
- 12
- References
- 45
- Citations by year
- 2026: 2 · 2025: 9 · 2024: 1
- FWCI
- 1.32
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Sensors (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Topics
- Physical Sciences › Engineering › Biomedical Engineering › Non-Invasive Vital Sign Monitoring
- Physical Sciences › Chemical Engineering › Bioengineering › Analytical Chemistry and Sensors
- Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Optical Imaging and Spectroscopy Techniques
- Keywords
- pulse oximetry, oxygen saturation, skin pigmentation, finger selection, measurement accuracy, Internet of Things, Munsell color system, heart rate monitoring
- MeSH terms
- Oxygen Saturation, Adult, Female, Fingers, Heart Rate, Humans, Male, Oximetry, Oxygen, Skin Pigmentation, Young Adult
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