Development and validation of a low-cost, wearable near-infrared spectroscopy system for quantifying tissue water fraction in the human brain.
Overview
Abstract
Significance: Cerebral water fraction is physiologically relevant to brain fluid dynamics, glymphatic function, cerebral edema, and dehydration, yet it is not routinely measured in wearable neuroimaging.
Aim: We aimed to develop and validate a low-cost, wearable, light-emitting diode (LED)-based continuous-wave near-infrared spectroscopy system capable of concurrently monitoring changes in cerebral hemoglobin concentration and water fraction from the forehead.
Approach: Our device, called the GS-FlexNIRS, contains nine LEDs spanning 740 to 1050 nm mounted on a flexible printed circuit board. Three of these wavelengths (i.e., 910, 940, and 1050 nm) fall within the water absorption window. A wavelength-weighted fitting algorithm incorporates measured LED emission spectra and photodiode responsivity to enable accurate chromophore recovery despite spectrally broad LED illumination. Performance was characterized in liquid phantoms and in five healthy participants during respiratory maneuvers.
Results: The system achieved a dynamic range of ∼100 dB, gain linearity (R2>0.99997), and signal-to-noise ratio of 67 to 90 dB. Phantom experiments confirmed independent tracking of hemoglobin deoxygenation and water fraction changes. Hemoglobin responses in human measurements were consistent with prior work.
Conclusions: The GS-FlexNIRS (∼$350/
Reproduced under the paper's license (CC BY), from the paper cited above.
Code
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Code and Data Availability
The data that support the findings of this study are available from the corresponding author upon reasonable request. The analysis code used in this study is available from the corresponding author upon reasonable request.
Reproduced under the paper's license (CC BY), from the paper cited above.
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Version 1, 30 October 2026: the first record
Recorded: type, language, journal, volume, issue, pages, dates, 8 authors, 6 keywords, 14 MeSH terms, 1 funder, 70 references.
Cite
This paper
Wu, K. C., Renna, M., Otic, N., Starkweather, Z., Kierul, O. S., Smith, C., Franceschini, M. A., & Robinson, M. B. (2026). Development and validation of a low-cost, wearable near-infrared spectroscopy system for quantifying tissue water fraction in the human brain. Journal of biomedical optics, 31(10), 106006. https://
BibTeX
@article{wu2026developme
author = {Wu, Kuan Cheng and Renna, Marco and Otic, Nikola and Starkweather, Zachary and Kierul, Olivia S and Smith, Christopher and Franceschini, Maria Angela and Robinson, Mitchell B},
title = {{Development and validation of a low-cost, wearable near-infrared spectroscopy system for quantifying tissue water fraction in the human brain}},
journal = {Journal of biomedical optics},
year = {2026},
month = oct,
volume = {31},
number = {10},
pages = {106006},
publisher = {Society of Photo-Optical Instrumentation Engineers},
issn = {1083-3668},
doi = {10.1117/
url = {https://
pmid = {42953459},
pmcid = {PMC13715939}
}
RIS
TY - JOUR
AU - Wu, Kuan Cheng
AU - Renna, Marco
AU - Otic, Nikola
AU - Starkweather, Zachary
AU - Kierul, Olivia S
AU - Smith, Christopher
AU - Franceschini, Maria Angela
AU - Robinson, Mitchell B
TI - Development and validation of a low-cost, wearable near-infrared spectroscopy system for quantifying tissue water fraction in the human brain
T2 - Journal of biomedical optics
J2 - J Biomed Opt
PY - 2026
DA - 2026/
VL - 31
IS - 10
SP - 106006
SN - 1083-3668
PB - Society of Photo-Optical Instrumentation Engineers
DO - 10.1117/
UR - https://
LA - en
ER -
CSL-JSON
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"author": [
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