Medical Technology

Expert Descriptions and Explanations on different pieces of medical technology, how they work, what they are used for and what is up and coming exciting new research!

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.