fotopletysmograafia

Fotopletysmograafia, often abbreviated as PPG, is a non-invasive optical technique used to detect volumetric changes of blood in blood vessels. This is achieved by shining light through a translucent part of the body, such as a fingertip or earlobe, and measuring the amount of light that is absorbed or reflected. As the heart pumps blood, the volume of blood in the vessels changes, causing a corresponding fluctuation in light absorption. These fluctuations can be measured and translated into a waveform that represents the pulsatile nature of blood flow.

The basic principle relies on the fact that oxygenated hemoglobin and deoxygenated hemoglobin absorb light differently. By using wavelengths of light that are differentially absorbed by these two types of hemoglobin, PPG can provide information about blood oxygen saturation, a measure known as SpO2. The most common device utilizing PPG is the pulse oximeter, which clips onto a finger and displays both the pulse rate and SpO2.

Beyond pulse oximetry, PPG has found applications in various fields. In healthcare, it is used for continuous monitoring of vital signs, detecting arrhythmias, and assessing peripheral circulation. In sports and fitness, PPG sensors are integrated into wearable devices like smartwatches to track heart rate and activity levels. Research is also exploring its use in detecting a wider range of physiological parameters, including blood pressure and even certain neurological conditions, though these applications are still largely in the experimental phase. The simplicity and low cost of PPG technology make it a versatile and widely adopted method for physiological monitoring.