Fotopletysmografia

Fotopletysmografia, often abbreviated as PPG, is a non-invasive optical measurement technique that can be used to detect volumetric changes in blood within a specific region of the body. It works by shining light, typically red or infrared, onto the skin and measuring the amount of light that is reflected or transmitted.

The principle behind PPG is that blood absorbs light differently than surrounding tissues. As blood circulates through the vessels, the volume of blood in a particular area changes with each heartbeat. During systole, when the heart pumps blood, the blood volume increases, leading to greater absorption of light. During diastole, when the heart relaxes, the blood volume decreases, resulting in less light absorption. The PPG sensor detects these fluctuations in light absorption and converts them into an electrical signal that represents the pulse waveform.

PPG sensors are commonly found in wearable devices like smartwatches and fitness trackers, where they are used to monitor heart rate and blood oxygen saturation (SpO2). They can also be employed in medical settings for a variety of applications, including the assessment of peripheral circulation, the detection of arrhythmias, and as a component in pulse oximetry. The simplicity, low cost, and non-invasive nature of PPG make it a widely adopted technology for physiological monitoring.