Registering and Processing of a Photoplethysmography Signals

Heart rate variability (HRV) is a non-invasive indicator of the condition of the cardiovascular system. To calculate HRV, the time between two adjacent R peaks of the electrocardiogram of the individual is used, i.e. between two heartbeats. This method requires the placement of electrodes in certain places on the body of the individual. An alternative way to measure heart rate is to use the change in blood volume in the blood vessels, through optical method, so-called photoplethysmography. It is based on the measurement of the change in light absorption depending on the amount of blood in the blood vessels. This article discusses ways to capture photoplethysmographic signals and convert them into data suitable for further processing. Graphs of the data from experimental studies at different stages of their processing are presented.