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Mobile phone camera-based SpO2 measurements using broadband light and colored paper filters (Conference Presentation)
Author(s): Morris Vanegas; Anh Phong Tran; Elmar Laistler; Qianqian Fang
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Paper Abstract

The mobile health field has given rise to a surge of point-of-care diagnostic attachments for mobile phones. These attachments, however, are limited in adoption in low-resource settings due to initial acquisition and subsequent maintenance cost challenges. Point-of-care devices that require no or minimum attachment can make a great impact to the accessibility of such devices in resource-poor regions. In this abstract, we report a simulation study to demonstrate the feasibility of using an ultra-low-cost color-paper filter and a mobile phone to perform broadband pulse oximetry. We run a series of GPU-based Monte Carlo simulations using a previously segmented 7T MRI scan of a finger 3D model. We sweep the optical properties of the finger tissues between the wavelengh band of 400-800 nm with a 1 nm increment, with intensity based on the measured spectrum of an iPhone 8’s LED. We also measured the transmission spectra from paper filters of various colors, which we used to further alter the light source spectrum. Using a discretized photoplethysmogram (PPG) signal, we simulate a 60 bpm oscillation optical measurements due to an up to 15% volume changes of the finger arterioles. Simulations were repeated for various peripheral blood oxygen levels (SpO2). Finally, we estimate the SpO2 using the simulated PPG signals using the Ratio of Ratios (RR) method. We evaluate the performance of different color paper filters by comparing 1) total optical signal intensity, 2) maximum magnitude of the RR signal variations and 3) the correlation of the computed and assumed SpO2 values. We found that the purple-colored filter produced the highest RR signal variations and the cyan-colored paper resulted in the largest SpO2 changes in the tested range.

Paper Details

Date Published: 7 March 2019
Proc. SPIE 10869, Optics and Biophotonics in Low-Resource Settings V, 1086914 (7 March 2019); doi: 10.1117/12.2510896
Show Author Affiliations
Morris Vanegas, Northeastern Univ. (United States)
Anh Phong Tran, Northeastern Univ. (United States)
Elmar Laistler, Medizinische Univ. Wien (Austria)
Qianqian Fang, Northeastern Univ. (United States)

Published in SPIE Proceedings Vol. 10869:
Optics and Biophotonics in Low-Resource Settings V
David Levitz; Aydogan Ozcan, Editor(s)

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