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. 2021 Dec 24;322(4):H493–H522. doi: 10.1152/ajpheart.00392.2021

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Copyright © 2022 The Authors

Licensed under Creative Commons Attribution CC-BY 4.0. Published by the American Physiological Society.

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Figure 1. — Devices for measuring the photoplethysmogram (PPG) signal. The PPG can be measured by several clinical and consumer devices, including (clockwise from top left): wristbands, pulse oximeters (×2), smart rings, hearables, smartwatches (×2), webcams, and smartphones. Sources (clockwise from top): P. H. Charlton, Max Health Band (“https://commons.wikimedia.org/wiki/File:Max_Health_Band.jpg”) (“https://creativecommons.org/licenses/by/4.0/” CC BY 4.0); P. H. Charlton, Wrist pulse oximeter (“https://commons.wikimedia.org/wiki/File:Wrist_pulse_oximeter.jpg”) (“https://creativecommons.org/licenses/by/4.0/” CC BY 4.0); Stefan Bellini, Pulox Pulse Oximeter (“https://commons.wikimedia.org/wiki/File:Pulox_Pulse_Oximeter.JPG”) (“https://creativecommons.org/publicdomain/zero/1.0/” CC0 1.0) M. Verch, https://flickr.com/photos/160866001@N07/32586534637/ (“https://creativecommons.org/licenses/by/2.0/” CC BY 2.0); S. Passler et al. (242) https://doi.org/10.3390/s19173641 (“https://creativecommons.org/licenses/by/4.0/” CC BY 4.0); GEEK KAZU, https://www.flickr.com/photos/152342724@N04/36729615770/ (“https://creativecommons.org/licenses/by/2.0/” CC BY 2.0); L. Chesser, Apple_Watch_user_(Unsplash) (“https://commons.wikimedia.org/wiki/File:Apple_Watch_user_(Unsplash).jpg”) “https://creativecommons.org/publicdomain/zero/1.0/” CC0 1.0); Peter H. Charlton, Webcam on computer screen (“https://commons.wikimedia.org/wiki/File:Webcam_on_computer_screen.jpg”) (“https://creativecommons.org/licenses/by/4.0/deed.en” CC BY 4.0); (centre) P-H. Chan et al. (243) https://doi.org/10.1161/JAHA.116.003428 (Creative Commons Licence).