Blood Oxygen Saturation Measurement Using Polarization-Dependent Optical Sectioning

• Published in: IEEE sensors journal Vol. 17; no. 12; pp. 3900 - 3908
• Main Authors: Mishra, Deepak, Priyadarshini, Neha, Chakraborty, Supriya, Sarkar, Mukul
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.06.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: bio-signal; Blood; Correlation coefficients; deep layer; Human performance; Light sources; linearly polarized light; Luminous intensity; Measurement techniques; Measuring instruments; Monitoring; Optical imaging; Optical sectioning; Oxygen content; Polarization; Real time; Sensors; Skin; SpO; superficial layer; White light
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2017.2698520

Blood oxygen saturation (SpO 2 ) measurement is a routinely performed clinical procedure involved in the diagnosis of several critical diseases. However, the most commonly used SpO 2 measuring device, known as oximeter, becomes unreliable in the absence of proper body contact. A non-contact, noninvasive, real-time device is desirable for accurate measurement and continuous monitoring of SpO 2 . This paper presents a polarized imaging-based integrated solution for SpO 2 measurement. The polarization filters are used to separate light components reflecting from deep and superficial layers of skin. The ratio of intensities of the two components is found to have a linear relationship with SpO 2 levels. In contrast to the existing SpO 2 measurement techniques, the proposed method uses a single light source. The experiments are performed with 15 human subjects (11 male and 4 female) using different wavelengths of light. A statistically significant relationship is observed between SpO 2 and the intensity ratios for red light (correlation coefficient r = 0.6426 with p=0.001965 and mean error = 0.0626). The experiments are repeated using white light, and a similar relationship is observed (r = 0.5603 with p = 0.00947 and mean error = -0.9289). Furthermore, the Bland-Altman analysis shows that the results of the proposed method are consistent with the reference data. This suggests that a real-time integrated polarized imaging-based SpO 2 measurement device can be developed based on the proposed method.