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Science and Technology

Curious Cyborg informative section on the world of Science and Technology. Includes authoritative resources in some science subjects, as well as reviews, recommendations and guides to technology and gadgets

history of PPG, red PPG on black

The Fascinating History of Photoplethysmography

The Photoplethysmogram, or PPG was first observed in 1936, by Alrick B. Hertzman who coined the term “Photoelectric Plethysmograph” due to the fact that the technique relied on using a light source and photocell (Photoelectric) to observe the light interaction with tissue. Hertzman theorized the regular pulsations that were seen could only be caused by the changing volume of blood in tissue synchronous with the beating of the heart (Plethysmograph). The term has more or less stuck, now shortened simply to Photoplethysmography or PPG.