fotoplethysmografische

Fotoplethysmography, often abbreviated as PPG, is a non-invasive optical technique used to measure changes in blood volume within peripheral tissues, typically in the fingers, toes, or earlobes. The method relies on the principle that light absorption in biological tissues varies with blood volume, allowing for the detection of pulsatile blood flow. PPG is commonly employed in medical diagnostics, fitness tracking, and consumer electronics, such as smartwatches and pulse oximeters.

The device used in PPG typically consists of a light-emitting diode (LED) and a photodetector. The LED emits light at specific wavelengths, usually in the red or infrared spectrum, which penetrates the skin and is absorbed by hemoglobin in the blood. The photodetector measures the amount of light that passes through or is reflected back from the tissue. As blood volume fluctuates with each heartbeat, the detected light signal varies, producing a waveform that corresponds to the pulse.

PPG is widely utilized in pulse oximetry to monitor oxygen saturation levels (SpO₂) in blood, heart rate, and sometimes even respiratory rate. Its portability and low cost make it a popular choice for continuous monitoring in both clinical and home settings. However, PPG measurements can be influenced by factors such as motion artifacts, skin pigmentation, and ambient light, which may affect accuracy.

Beyond medical applications, PPG is integrated into wearable technology to track physical activity, sleep patterns, and stress levels. While highly convenient, its reliability depends on proper calibration and user adherence to measurement guidelines. Research continues to explore its potential in detecting additional physiological parameters, such as blood pressure and arterial stiffness.