Heartbeat sensor contains Phototransistor and IR LED to detect the pulse of the human. The heartbeat is the sound of contraction/relaxation of Valves as the blood passes from one region to another.
The Heartbeat detector sensor works on the principle of photoplethysmography. The main aim is to measure the volume of blood flowing through an organ. When there is a large volume of blood, light intensity through that organ varies. The heartbeat calculated by the flow of blood and the absorption of light by the blood flow in that organ. The timing of pulse is important and according to that signal pulses generated equals to the heartbeat pulse.
Light eject from the light emitting device transmits through any vascular region of the body like earlobe and received by the detector.
The combination of the LED and Photodetector acts as a Heartbeat Detector. When tissue is in a light source, the light is either absorbed or reflected. Some of the light is absorbed and others reflected, the reflected light is received by the detector. The amount of light absorption depends on the volume of blood in that organ. The output is directly proportional to the heartbeat.
DC output signal corresponds to the tissues and volume of blood and the changes in the pulse superimposed on the DC signal. The AC signal synchs with the heartbeat and converted into DC using ADC. The digital pulses are given to a microcontroller for calculating the heartbeat rate, given by the formula-
BPM(Beats per minute) = 60*f; f is the pulse frequency
- S connect to Arduino pin Analog 0 / A0
- Positive connect to Arduino pin 5+
- Negative pin – connect to Arduino pin GND