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  • Writer's picturePerceptive Things Team

What is a Motion Sensor (AKA Detector)

Motion sensors can be useful for keeping tabs on what is going on around you.

Motion sensors work best when they are part of an IoT-Enabled smart home detection system. These cloud-based systems help you gain insight that keeps you, your possessions, and your buildings safe.

Whether you are looking for your first motion sensor or are looking to create an interconnected system of sensors, this is the article for you! We will discuss everything you need to know about motion sensors and how they can help you.

What is a motion sensor?

A motion sensor, also known as a motion detector, is an electronic device used to detect the movement of objects. It is usually placed in areas where movement is most likely to occur, such as the doorway or hallway.

Another use for motion sensors is to track the movement of your important equipment or other assets.

Whenever it detects movement, it sends a signal that alerts you within seconds. Most motion sensors are able to alert you via text, call, and email.

Motion sensors are typically made up of two key parts:

  • The sensor itself: It detects the movements of the object or person in its vicinity.

  • Control panel: It processes the movement information and sends an alert or notice to the security system or other devices.

Features of motion sensors

Since their creation in the 1940s, motion sensors have been enhanced with a range of useful features. Selecting a motion sensor for your building is dependent on what kind of data you hope to track and receive alerts on.

You can select the features that work for you by considering if you will need information on building security, maintenance, foot traffic, or equipment location.

Here are some common motion detector features:

  • Motion-activated

  • Remote access capabilities (so you can adjust the settings from afar)

  • Configurable sensitivity levels

  • Configurable alert thresholds

  • Long-range motion tracking

  • Adhesive types (magnetic, wall mount, M3, etc.)

  • Waterproof

  • Extended battery life

How motion sensors are useful for commercial buildings

Commercial buildings often have a large number of unknown visitors. From customers to custodians, there are many people who will be in and out of the building throughout the day.

This means that these types of buildings have both security and safety concerns to consider when it comes to protecting the building. That is why it may be helpful to have more than one type of motion sensor in place.

Some motion sensors are ideal for tracking occupancy while others are best used for monitoring the movement of important equipment, such as fire extinguishers.

Below, we will outline these two popular uses for motion sensors to help you determine which uses may be relevant for your building.

Tracking Occupancy

Occupancy Sensor Example
Occupancy Sensor Example

To the left is an image of a room motion sensor, often referred to as an "occupancy sensor".

Occupancy sensors do not need a lot of motion to be triggered. They are often used to activate other tools in spaces, such as turning on the air conditioning or lights in a room.

You can also use these occupancy sensors to determine which areas of your building are less frequented. This allows you to reduce energy consumption within specific areas or even redesign the space so that it can be used more efficiently.

Tracking equipment and assets

Motiv™ by Perceptive Things®

Another excellent use for motion sensors is to monitor your equipment and assets. At Perceptive Things®, we've created our Motiv™ motion sensor based on multi-family and commercial buildings' unique needs.

Simply attach Motiv™ to any piece of equipment and can alert you when the asset is moved or is vibrating for longer than a configurable duration.

Motiv™ can be used to track things like cart usage, door openings, or other items like fire extinguishers when they are moved from their installed locations.

How different types of motion sensors work

Another aspect to consider when it comes to understanding and selecting motion sensors is how they function. You might be surprised to learn that most motion sensors are actually either monitoring the energy levels within the room or detecting changes to these levels.

The methods that your motion sensor uses depend on what type of sensor you have.

Here are the different types of motion sensors:

  • Passive Infrared (PIR) Sensors

  • Active Sensors

    • Ultrasonic sensors

    • Microwave sensors

    • Tomographic sensors

  • Dual Sensors

Passive Infrared (PIR) sensors

Passive Infrared (PIR) sensors, also referred to as Passive Infrared (PID) Detectors measure the infrared light that radiates off of objects and people. These can be thought of as "read-only" devices as they are only monitoring energy, rather than sending it out.

According to NASA, infrared light is the radiant heat that comes off of an object. When the PIR detects this heat, it causes the motion sensor to send electrical data to its control panel. This, in turn, triggers an alert to be sent to you!

PIRs tend to be used for security alarms or for automatic lighting but they do have some limitations. PIRs can only tell you that movement has taken place, but do not provide information as to the context. These sensors will not tell you what or who triggered the alarm.

Another limitation is that they are not trackers and will not inform you as to where the person or item has gone. This is why motion sensors are best paired with additional types of sensors to create a detection system. This can give you more detailed insights into your building than if you were to use a standalone sensor.

Active sensors

Active sensors are a type of radar technology that has both a receiver and a transmitter. This is different from passive sensors because active sensors are able to send energy out.

Active sensors send out waves of energy and are able to detect when there is a difference in interference. This change in the environment would then trigger an alert to be sent. The sensitivity of an active sensor depends on the type of energy waves they transmit.

Here are the 3 most common active sensors:

Dual sensors

Dual technology motion sensors work by combining PIR and active sensor technologies within the same sensor to avoid false alarms.

To activate dual sensors, both active and PIR sensors must be triggered to send an alarm. And since these sensors all work differently, false alarms tend to be less frequent.


We hope that this comprehensive introduction to motion sensors helps you choose the right device for your building. After learning what motion sensors are and how they work, you now understand why they are considered the backbone of any good building monitoring system.

Regardless of what your needs are, motion detectors are a perfect way to keep you and your tenants! If you still have questions, suggestions, or comments about motion sensors, let us know via the comments section below.

Have you used a motion sensor before? What kinds of smart devices do you use to prevent damage in your building? Drop us a note in the comments, we'd love to hear from you!

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