TY - JOUR
T1 - Self-Calibration Phenomenon for Near-Infrared Clinical Measurements
T2 - Theory, Simulation, and Experiments
AU - Feder, Idit
AU - Duadi, Hamootal
AU - Chakraborty, Ruchira
AU - Fixler, Dror
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/3/31
Y1 - 2018/3/31
N2 - An irradiated turbid medium scatters the light in accordance to its optical properties. Near-infrared (NIR) clinical methods, which are based on spectral-dependent absorption, suffer from an inherent error due to spectral-dependent scattering. We present here a unique spatial point, that is, iso-pathlength (IPL) point, on the surface of a tissue at which the intensity of re-emitted light remains constant. This scattering-indifferent point depends solely on the medium geometry. On the basis of this natural phenomenon, we suggest a novel optical method for self-calibrated clinical measurements. We found that the IPL point exists in both cylindrical and semi-infinite tissue geometries (Supporting Information, Video file). Finally, in vivo human finger and mice measurements are used to validate the crossing point between the intensity profiles of two wavelengths. Hence, measurements at the IPL point yield an accurate absorption assessment while eliminating the scattering dependence. This finding can be useful for oxygen saturation determination, NIR spectroscopy, photoplethysmography measurements, and a wide range of optical sensing methods for physiological aims.
AB - An irradiated turbid medium scatters the light in accordance to its optical properties. Near-infrared (NIR) clinical methods, which are based on spectral-dependent absorption, suffer from an inherent error due to spectral-dependent scattering. We present here a unique spatial point, that is, iso-pathlength (IPL) point, on the surface of a tissue at which the intensity of re-emitted light remains constant. This scattering-indifferent point depends solely on the medium geometry. On the basis of this natural phenomenon, we suggest a novel optical method for self-calibrated clinical measurements. We found that the IPL point exists in both cylindrical and semi-infinite tissue geometries (Supporting Information, Video file). Finally, in vivo human finger and mice measurements are used to validate the crossing point between the intensity profiles of two wavelengths. Hence, measurements at the IPL point yield an accurate absorption assessment while eliminating the scattering dependence. This finding can be useful for oxygen saturation determination, NIR spectroscopy, photoplethysmography measurements, and a wide range of optical sensing methods for physiological aims.
UR - http://www.scopus.com/inward/record.url?scp=85043449635&partnerID=8YFLogxK
U2 - 10.1021/acsomega.8b00018
DO - 10.1021/acsomega.8b00018
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C2 - 30221222
AN - SCOPUS:85043449635
SN - 2470-1343
VL - 3
SP - 2837
EP - 2844
JO - ACS Omega
JF - ACS Omega
IS - 3
ER -