Introduction to photoplethysmography

Photoplethysmography (PPG) is a noninvasive optical technique widely used in the study and monitoring of the pulsations associated with changes in blood volume in a peripheral vascular bed. Whether the term “plethysmography,” is a misnomer is a matter of debate which is still ongoing among the PPG community, yet the title has received general consent. This chapter presents a brief review of the history of PPG and introduces the chapters to be covered in this book.