The flat side of the sensor should be placed on top of the vein and a slight presser should be applied on top of it, normally clips or Velcro tapes are used to attain this pressure. Also it is not recommended to handle these sensors with wet hands. Since all the electronics on the sensor are directly exposed it is also recommended to cover the sensor with hot glue, vinyl tape or other non conductive materials. Using the pulse sensor is straight forward, but positioning it in the right way matters. If the flow of blood is detected then the ambient light sensor will pick up more light since they will be reflect ted by the blood, this minor change in received light is analysed over time to determine our heart beats. The veins will have blood flow inside them only when the heart is pumping, so if we monitor the flow of blood we can monitor the heart beats as well. Now the LED emits light which will fall on the vein directly. This can either be your Finger tip or you ear tips, but it should be placed directly on top of a vein.
The LED on the front side of the sensor is placed over a vein in our human body. This circuitry is responsible for the amplification and noise cancellation work. The sensor has two sides, on one side the LED is placed along with an ambient light sensor and on the other side we have some circuitry. The working of the Pulse/Heart beat sensor is very simple. Note: Complete technical details can be found in the Pulse Sensor Datasheet linked at the bottom of this page. It is purely intended for hobby projects/demos and should not be use for health critical applications. Warning: This sensor is not medical or FDA approved.
Biometric Pulse Rate or Heart Rate detecting sensor.