Skin pigmentation effect of NIRS measured tissue oxygenation: Phantom Study
Disciplines
Bioimaging and Biomedical Optics | Biomedical | Electromagnetics and Photonics | Molecular, Cellular, and Tissue Engineering
Abstract (300 words maximum)
Accurate near-infrared spectroscopy (NIRS) measurements across diverse populations remain an open challenge due to the optical absorption of melanin in the skin. This can bias oxygen saturation (SO₂) estimates. As NIRS becomes increasingly adopted for wearable neuromonitoring and clinical use, understanding and mitigating pigmentation-related signal variation is essential for equitable and reliable brain sensing. This study aims to introduce a controllable, layered tissue mimicking phantom designed to isolate and quantify the impact of epidermal pigmentation on continuous-wave NIRS oximetry. The platform replicates the optical structure of human tissue using PDMS layers infused with nigrosine and India-ink-based absorbers to emulate the epidermis and scalp respectively, while a circulating vessel module containing hemoglobin solution models dynamic cerebral blood oxygenation. Using FlexNIRS, a wearable dual-wavelength oximeter operating at 735 and 850 nm, we systematically varied epidermal melanin concentration, layer thickness, and blood oxygenation levels while recording device intensity signals and oxygenation estimates. This approach enables precise characterization of how pigmentation influences measured optical intensity, signal-to-noise ratio, and SO₂ accuracy. The results will inform the development of pigmentation-aware calibration models and correction factors, ultimately improving the accuracy and inclusivity of wearable NIRS technologies.
Use of AI Disclaimer
no
Academic department under which the project should be listed
SPCEET – Electrical and Computer Engineering
Primary Investigator (PI) Name
Paul Seung Yup Lee
Skin pigmentation effect of NIRS measured tissue oxygenation: Phantom Study
Accurate near-infrared spectroscopy (NIRS) measurements across diverse populations remain an open challenge due to the optical absorption of melanin in the skin. This can bias oxygen saturation (SO₂) estimates. As NIRS becomes increasingly adopted for wearable neuromonitoring and clinical use, understanding and mitigating pigmentation-related signal variation is essential for equitable and reliable brain sensing. This study aims to introduce a controllable, layered tissue mimicking phantom designed to isolate and quantify the impact of epidermal pigmentation on continuous-wave NIRS oximetry. The platform replicates the optical structure of human tissue using PDMS layers infused with nigrosine and India-ink-based absorbers to emulate the epidermis and scalp respectively, while a circulating vessel module containing hemoglobin solution models dynamic cerebral blood oxygenation. Using FlexNIRS, a wearable dual-wavelength oximeter operating at 735 and 850 nm, we systematically varied epidermal melanin concentration, layer thickness, and blood oxygenation levels while recording device intensity signals and oxygenation estimates. This approach enables precise characterization of how pigmentation influences measured optical intensity, signal-to-noise ratio, and SO₂ accuracy. The results will inform the development of pigmentation-aware calibration models and correction factors, ultimately improving the accuracy and inclusivity of wearable NIRS technologies.