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Proceedings Paper

Double junction photodiodes for multiwavelength photoplethysmography
Author(s): João Costa; Hugo Vieira; Paula Louro; Manuela Vieira
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Paper Abstract

Oxygen saturation levels in blood are usually measured with photoplethysmography (PPG) using two LEDs, one in the red and the other in the near infrared region of the spectrum. A number of studies have increased the number of wavelengths, not only to improve the accuracy of SpO2 measurements, but also to provide real-time measurements of other substances in blood, such as methemoglobin and carboxyhemoglobin. In addition, analysis of PPG signals at different wavelengths could provide information about skin pathologies at various tissue depths. In this work we study the advantages of using photodetection based on vertically stacked double junction photodiodes. The sensitivity of such photodetectors over a wider wavelength range is of particular interest for PPG. We have implemented a test bed, which includes the control of light sources to emulate the transmitted signals, the analog front-end to recover the time multiplexed PPG signals and post-processing to calculate the hemoglobin fractions. We use this framework to compare results of photodetection obtained using a single silicon junction and the combination of a silicon and indium gallium arsenide junction for photodetection.

Paper Details

Date Published: 9 May 2018
PDF: 7 pages
Proc. SPIE 10680, Optical Sensing and Detection V, 106802H (9 May 2018); doi: 10.1117/12.2307286
Show Author Affiliations
João Costa, Instituto Superior de Engenharia de Lisboa (Portugal)
Instituto Politécnico de Lisboa (Portugal)
CTS-UNINOVA (Portugal)
Hugo Vieira, Instituto Superior de Engenharia de Lisboa (Portugal)
Instituto Politécnico de Lisboa (Portugal)
Paula Louro, Instituto Superior de Engenharia de Lisboa (Portugal)
Instituto Politécnico de Lisboa (Portugal)
CTS-UNINOVA (Portugal)
Manuela Vieira, Instituto Superior de Engenharia de Lisboa (Portugal)
Instituto Politécnico de Lisboa (Portugal)
CTS-UNINOVA (Portugal)


Published in SPIE Proceedings Vol. 10680:
Optical Sensing and Detection V
Francis Berghmans; Anna G. Mignani, Editor(s)

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