PIR sensor (Passive Infrared sensor), is a type of electronic device used to detect motion or the presence of humans and animals within its vicinity.


Used to detect motion by sensing changes in the infrared radiation emitted by objects within its field of view.


Amount of radiation emitted is directly related to the object's temperature







• Sensor has two slots or windows that allow the infrared radiation to reach the sensing element inside

• Inside the sensor, there's a pyroelectric material that generates a voltage when exposed to heat changes

• It has two sensing elements that detect infrared radiation. These sensors are arranged so that they detect the difference in heat levels between the two sensors.

• When a warm object moves within the sensor's field of view, it causes a change in the heat pattern detected by the two sensing elements. This change is interpreted as motion.

• If it detects a significant difference between the two sensors, indicating motion, it triggers an output signal.