Photoplethysmography (PPG) is a non-invasive, electro-optic method that provides information about the volume of blood flowing in a test region close to the skin. A photoplethysmography sign, illuminating the relevant area of the body and then reflecting or passing light from this region is obtained.
In order to obtain PPG, a light source with a wavelength λ is provided on one side of the finger, for example, to the finger, and a photodetector to capture the light transmitted to the opposite side of the source is placed.
This project describes the microcontroller based heart rate system. The change in blood volume at the fingertip of each beat is measured by optical sensors. At the tip of the finger placed on the sensor unit, the IR LED emits an infrared light and the phototransistor detects the ratio of the reflected light back. The intensity of the reflected light varies depending on the volume of blood at the fingertip. The amount of infrared light reflected in each heartbeat varies slightly, and this can be detected by the phototransistor. This small change can be converted into pulse by proper signal conditioning. In order to determine heart rate, microcontrollers and pulse pulses can be counted.
The basis of these measurements is the heart rate and order of the heart. At the same time, it plays an important role in the vessels that provide blood circulation.It can be defined as periodic distension propagating through arteries caused by blood pumping function of heart.
It depends on; elasticity, diameter, thickness, pressure.
Sphygmography is a pressure wave measurement. It is possible to measure from 0 to 1 bar (0 to to760 mmHg ).
Photoplethysmography (PPG) Light (visible + IR) is defined as application to subcutaneous area. (Allen, 2007).
There are two kind PPG ; Transmission PPG and Reflective PPG.These separate according to transmission or reflection of light.
Sensors are place on the places with good blood perfusion e. g. finger tips, ear lobes.
The analysis of pulse wave propagation in arteries occurs by combining the following steps. PCB (Printed Circuit Board) ,Electronic interface ,Sensor ,Final realization.
