Features and Applications of Motion Detectors

Motion detectors are motion-sensitive devices which track physical movement within an area and alert the user or perform a specific task. These devices work with multiple technologies using microwaves, ultrasonic waves, and so on.

Motion detectors are the primary choice for security purposes in households, industries, and commercial establishments. They are also deployed to enhance the customer experience of gadgets, in the medicinal field for Bio-monitoring and Bio-chemical detection in patients.


Motion sensors are of two types- Passive Infrared Sensors and Active Infrared sensors.

A passive infrared sensor detects the presence of human beings or animals when the temperature of the intruding object varies from that of the background objects in the area. Most contact sensors are Passive Infrared sensors. These sensors don’t emit any form of radiation; hence are called Passive IR sensors.


Active sensors are of various types depending on the radiation the device emits to detect movements.

Ultrasonic – The device works by emitting high-frequency sound waves and change in the wave pattern triggers the motion sensors.

Microwave -These devices emit electromagnetic radiations that bounce back to the sensors when interrupted. It is detected by microwave sensors that turn off the alarm.

Tomographic – This technology uses radio waves. When it detects a change in the wave pattern, it triggers the sensors.

Area Reflective – The reflection of Infrared rays emitted by LED is used to identify objects in a particular area.


Both Passive and Active Infrared Sensor Technologies can be incorporated in a single device for a more accurate detection avoiding false alarm, as both the sensors have to trip for it to notify the user.

Examples: PIR and Ultrasonic


Key features to look for in Motion detectors:


Pet Immune – This feature reduces false alarm in case of heat detection caused by pet/animal intrusions.


Video capability feature – Devices with video recording feature can be a perk. If the sensor trips, the recording starts automatically, which saves on memory and can also be a piece of evidence for the incident.


Wireless motion sensors – Wireless sensors are more convenient for security uses. It is the most common type used today because of its simpler setup.


Higher dense of field view – Higher dense of field view for PIR sensors as it helps detect small movements.


Application of Motion Sensors


It is important to place the Sensors at the right place and angle to avoid causing a false alarm.


  • Avoid placing Sensors close to heat vents or drafty places that can easily trip the sensors due to temperature shifts.
  • Place the sensors opposite to doorways or entrances so that the device senses movement at the earliest.
  • Avoid blocking the sensors by placing them above tall furniture. It can restrict the infrared radiation as it doesn’t penetrate through hard objects like furniture.
  • Test the motion sensors for the right area and its functioning as per your expectations.
  • Dust particles on the sensors can restrict the functioning of the sensors; hence regular maintenance of the devices is necessary.


There are various uses of motion sensors. It is necessary to be aware of the right kind of sensors and their functions for the particular area and task before installation.

No comments yet.

Leave a Comment

Let us know your thoughts on this !