During the cardiac relaxation period (diastolic period) the pressure decreases, the density increases and the physical dimension of the tips of the fingers decreases. At every heartbeat the arterial blood pressure raises (systolic period) and the dimension of the tips of the fingers slightly increases, while the higher oxygenation causes the decrease of the optical density of the skin tissue. Since these cyclical variations follow the cardiac rhythm, they can be used to measure the frequency of the peripheral pulsations.
Circuit blocks of Pulse Rate
Effects of the temperature on the measurement of the frequency of the pulsations
Recordings of the peripheral pulsations in a finger
Effects of breathing and exercising on the frequency of the pulsations.
Theoretical topics:
Measurement of the cardiac frequency
The use of optical sensors
Comparator with hysteresis for the processing of the signal provided by the optical sensor
Concept of cardiac rhythm and typical values, in different subjects and in different conditions of the subject.
