The modern world is filled with gadgets that get excited when they sense human motion. Automatic doors in elevators and shopping malls, burglar alarms at houses and shops, automatic lighting systems, electronic amenities in washrooms are just a few examples where human presence or absence puts the device into active or passive state.  Smart, right? Now, what if we tell you that behind this smart response to motion is a gizmo that does not even reach the 2cm mark in size. Known as Pyroelectric or Passive Infrared Sensor (PIR, in both cases), this small electronic device is the curious case for this Insight.How does PIR sensor selectively responds to human radiated IRs? Upto what range can this sensor work? What lies inside this sensor that makes it work? This and answers to more questions in this Insight on PIR sensors. What adds more charm to this Insight is that the Panasonic 10m sensor taken is also one of the smallest PIR sensors commercially available till date.  

The term ‘Motion detectors’ can be used to refer to any kind of sensing system which is used to detect motions; motion of any object or motion of human beings. However, it is primarily used to detect motion of human beings or in other words, presence of a body in a certain area. A motion detector is an electronic device that detects the physical movement in a given area/ designated locations and it transforms motion into an electric signal. Motion sensors are commonly used in security systems as triggers for automatic lights or trips for remote alarms and similar applications. Motion sensors work based on a wide variety of principles and is used in a wide variety of applications. Typical usage could be in the exterior doorways or windows of a building for monitoring the area around the building.