A Self-Calibrated Single Wavelength Biosensor for Measuring Oxygen Saturation

Michal Katan, Ori Pearl, Alon Tzroya, Hamootal Duadi, Dror Fixler

Research output: Contribution to journalArticlepeer-review


Traditional methods for measuring blood oxygen use multiple wavelengths, which produce an intrinsic error due to ratiometric measurements. These methods assume that the absorption changes with the wavelength, but in fact the scattering changes as well and cannot be neglected. We found that if one measures in a specific angle around a cylindrical tissue, called the iso-pathlength (IPL) point, the reemitted light intensity is unaffected by the tissue’s scattering. Therefore, the absorption can be isolated from the scattering, which allows the extraction of the subject’s oxygen saturation. In this work, we designed an optical biosensor for reading the light intensity reemitted from the tissue, using a single light source and multiple photodetectors (PDs), with one of them in the IPL point’s location. Using this bio-device, we developed a methodology to extract the arterial oxygen saturation using a single wavelength light source. We proved this method is not dependent on the light source and is applicable to different measurement locations on the body, with an error of 0.5%. Moreover, we tested thirty-eight males and females with the biosensor under normal conditions. Finally, we show the results of measuring subjects in a hypoxic chamber that simulates extreme conditions with low oxygen.

Original languageEnglish
Article number132
Issue number3
StatePublished - 4 Mar 2024

Bibliographical note

Publisher Copyright:
© 2024 by the authors.


  • biosensor
  • light-tissue interaction
  • oxygen saturation
  • scattering
  • tissue diagnostics optics


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