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Proceedings Paper

Utilizing an open-microcavity optoacoustic sensor for spectroscopic determination of methemoglobin concentration
Author(s): Ralph W. Peterson; Kavya Kadugodinandareddy; Vinitha Karunakaran; Casey Whitney; Jian Ling; Jing Yong Ye
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Paper Abstract

We present a simple, non-destructive photoacoustic spectroscopy method utilizing a unique open-microcavity optoacoustic sensor to measure the concentration ratio of Methemoglobin (MetHb) in an optically scattering medium. Elevated levels of MetHb, present for example in the blood disorder Methemeglobinemia, cannot be detected by conventional pulse oximetry, and may result in inaccurate arterial oxygen saturation measurements. Samples with different ratios of Oxygenated Hemoglobin (HbO2), Deoxygenated Hemoglobin (HHb), and MetHb were obtained and mixed with nanoscale latex beads to present an optical scattering effect. Polymer encapsulated hemoglobin (PEH) samples were also studied. A sample chamber containing 20 μL of each sample was positioned directly underneath our patented optoacoustic sensor. Unlike a piezoelectric transducer, our optoacoustic sensor allows an excitation laser beam from an OPO laser to pass through and be absorbed by the sample to produce a photoacoustic signal. The cavity layer of the optoacoustic sensor is exposed directly to the resulting ultrasound signal, which causes an intensity modulation of a HeNe laser that is used to monitor the resonance condition of the sensor. A probe laser beam is total internally reflected off of the sensor and detected with a fiber-coupled APD detector. Three wavelengths are chosen for our excitation laser based on the absorption peaks and isobestic points of HHb, HbO2, and MetHb. Using established values of the molar extinction coefficients of HbO2, HHb, and MetHb a set of three simultaneous equations can be solved to accurately determine the concentration ratio of MetHb.

Paper Details

Date Published: 5 March 2015
PDF: 8 pages
Proc. SPIE 9319, Optical Tomography and Spectroscopy of Tissue XI, 93191N (5 March 2015); doi: 10.1117/12.2080119
Show Author Affiliations
Ralph W. Peterson, The Univ. of Texas at San Antonio (United States)
Kavya Kadugodinandareddy, The Univ. of Texas at San Antonio (United States)
Vinitha Karunakaran, The Univ. of Texas at San Antonio (United States)
Casey Whitney, The Univ. of Texas at San Antonio (United States)
Jian Ling, Southwest Research Institute (United States)
Jing Yong Ye, The Univ. of Texas at San Antonio (United States)

Published in SPIE Proceedings Vol. 9319:
Optical Tomography and Spectroscopy of Tissue XI
Bruce J. Tromberg; Arjun G. Yodh; Eva Marie Sevick-Muraca; Robert R. Alfano, Editor(s)

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