How PIR Sensor Works

When it comes to enhancing your home`s or even business`s security intelligence and management, installing a PIR sensor can be an excellent investment. You can use the device to determine whether a person has moved in or out of the sensor range within your home or business. I know you might be wondering how this could be possible. So, let`s see…

How PIR Sensor Works

First, how do you think the PIR sensor works? Does it have a camera lens, or how is it sensing motion? Let`s find out. Below

PIR is an inspired innovation in motion detection that uses two photoactive diode areas of a pyroelectric sensor in converting the infrared light emitted from an object into an electrical charge. These pair of pyroelectric sensors are positioned next to each other and any charges in the signal variance between the two sensors will result in the activation of the motion sensor.

PIR sensor has a total of four photoactive diode areas, hence minimizing possible false alarms that might be generated and enhancing the device`s performance and accuracy. PIR also has state-of-the-art motion sensors that offer support for internet connectivity and hence can be easily integrated into the Internet of Things software (IoT). This enables the incorporation of occupancy measurements with the output of other sensors boosting the building intelligence and supervision. 

What Are PIR Motion Sensors?

Well, now that you know how PIR works, let`s understand what PIR Motion Sensor is, and by the way, what is PIR Motion Sensor? Check below:

PIR or Passive Infra Red Sensor is a device used to detect and measure infrared light radiation from humans or animals. PIR Sensor is capable of detecting the movements of animals or humans within a fixed range.

The device is capable of detecting any object with temperatures above zero degrees because any object having temperatures above zero degrees radiates IR. The more an object`s temperature is getting higher, the more it is detected by PIR. 

PIR Sensory Types

Below are the types of PIR sensors:

  • Thermal Infrared Sensor

A thermal infrared sensor is a sophisticated device that detects an object by using heat energy emitted by the object in the form of infrared radiation. Can you imagine a world where the invisible heat radiation becomes visible through thermal infrared sensors, it is here with us!

The infrared sensor has a technology capable of revealing information that has been hidden from sight for a very long period. Thermal Infra-red sensors have found their way through different sectors, for instance, firefighters use them to navigate through smoke-filled environments. Although, these types of PIR sensors are slow when it comes to performance and accuracy.

  • Quantum Infrared Sensor

In the world of technology, boundaries are continuously being pushed, quantum infra-red sensors being at the forefront of this excellent evolution. Just like thermal infra-red sensors, quantum infra-red sensors also detect motion of objects within a specified range and I know you might be wondering how?

Quantum infra-red sensor is set to transform how humans perceive and interact with the environment. This device senses photons that depend on wavelength. It exploits the unique characteristics of quantum particles to realize significant sensitivity and accuracy.

Through leveraging the principles of quantum entanglement and superposition, quantum infra-red sensors are capable of detecting even the faintest traces of infra-red rays. As a result, quantum infrared sensors are significantly fast in their performance and accuracy, however, they need regular cooling for exact measurement.

Speculations and Features

Below are the speculations and features of the PIR sensor:

  1. Recommended input, +5V
  2. Output, 3.3V
  3. PIR is capable of differentiating an object`s and a person`s movement.
  4. Has repeatable and non-repeatable operating modes
  5. Current drain: <60 uA
  6. Detection angle: < 140 °C
  7. Detection distance: 3-7 meters
  8. Blockade time by default: 2.5 s
  9. Working temperature range: – 20 to + 80 °C
  10. Low power usage: 65 mA

What Are the Pros and Cons of PIR Sensors?

When it comes to your family, home, and property, safety usually is the pinnacle of your mind. Therefore, you might be worried, about how can you offer legitimate protection to your family, home, and property.

Among the many available options, having a PIR sensor in your home, safeguarding your property and family would be exceptional. However, before we can continue further, let`s check below the advantages of a PIR sensor and also look at some drawbacks on the same:


  • Improved Home Security

When you install a PIR sensor you can guarantee that your home and property are safe from dangerous people like thieves and animals. PIR sensor detects when a human or animal gets in or out of its range.

In this way, when a thief or any intruder comes to your home, the sensor will detect them and send some alarm while some like the movement sensor floodlights will switch on lights thus scaring people with bad intentions or animals.

  • Energy Savings

Have you ever thought of how energy-saving these PIR sensors can be? Imagine you switch on your floodlights throughout the night, what amount of electricity is used? When you have PIR sensors floodlights, you do not have to leave your home lit the whole night. These devices will only activate and use your electricity when they detect an object or someone gets within their range.

While if nothing is detected, the lights definitely stay off till morning. This can be an excellent investment in your home’s security as it offers good security and at the same time saves you electricity.

  • Cost Saving

PIR sensors are usually not expensive while they also save a lot on cost. For instance, compared to the services of watchmen, you only require a one time investment to install a PIR sensor, while having a watchman will require you to give a monthly salary or so, to safeguard your property and family. If you have a PIR sensor, you only need to regularly inspect it and make sure it is in the right working condition.

  • More Lifespan

PIR sensor has an extraordinary lifespan which is between 4 to 7 years. This ensures that reasonable security is provided to your home and property throughout.

  • Reliability 

PIR sensors are quite reliable in motion detection for they are not affected by changes in ambient light. As a result, they work effectively both in light and dark conditions, thus giving you consistent performance and utmost accuracy.

  • Affordability

 PIR sensors tend to be more affordable compared to other motion detection technologies. The affordability makes the PIR sensors available for a wide range of applications ranging from small residential homes to large commercial projects.

  • Simple to Install

Installing a PIR sensor is a simple and straightforward process. A PIR sensor typically will need minimal wiring and you can easily integrate it into your electrical framework without struggling or extensive modification.

  • Low Maintenance

 Having no moving parts, PIR sensors have very low maintenance needs. Once you install your PIR sensor, it will function reliably without the need for regular replacements. 

  • Wide Field of View

PIR sensor covers relatively a wide area, hence it is suitable for installation where motion detection is needed across a large space. This feature contributes to its effectiveness in security frameworks.


  • Line of Sight Dependency

PIR sensors always rely on a clear line of sight for accurate detection of motion. This means that obstructions such as walls might significantly hinder the effective workability of these devices, hence a possible blind spot.

  • Single Dimensional Sensing

PIR sensor will primarily detect motion along a single plane. Any motion perpendicular to their detection range might not be detected hence limiting their application in certain projects.

  • Susceptible to False Alarm

PIR sensors can be triggered by rapid changes in temperatures, for instance, those from cooling or heating systems, hence triggering false alarms. Although manufacturers are implementing mechanisms to reduce false positives, inaccuracy still occurs occasionally.

  • Limited Functionality in Complex Environment

PIR sensors struggle to differentiate between genuine and irrelevant motion when installed in areas with regular background movement such as streets. Thus, the PIR sensor`s workability in such areas might be affected.

  • Non-discriminative Detection

PIR sensors detect any motion provided that it alters infrared radiation. A false positive alarm can be triggered even when it is just a pet moving objects that might change infrared radiation.

  • Slow Response to Stationary Objects

PIR sensors are designed to detect motion. Thus, they might not be effective in detecting stationary objects and these factors can be limiting for certain applications.

What is the Difference Between IR and PIR Sensors?

IR (Infrared Sensor) and PIR (Passive Infrared Sensor) are both important elements of modern electronics, functioning as essential appliances in several applications that involve motion detection as well as the measurement of temperature.

Although the two devices share a common feature which is the usage of infrared radiation in sensing motion, they differ in their various features and functions. Below is a guide that will help you understand the difference between these two important motion detection devices.

  • Principles of Operation

IR detects infrared radiation emitted or reflected by an object. IR sensor depends on the active interaction between the target object, the sensor`s receiver, and emitter mechanisms. IR sensor is mostly used in application such as remote controls, measurement of temperature, and presence detection.

PIR sensor on the other hand relies on the change in infrared radiation caused by a moving object to sense motion. PIR sensors have a mechanism that produces a voltage when exposed to differences in infrared radiation configurations. PIR sensors are commonly used in motion detection frameworks for security as well as lighting control.

  • Functionality

IR sensors due to their adaptability, can be used in a number of applications. For example, temperature measurement, object detection, and communication. IR sensors emit infrared light and measure the reflected radiation in collecting data about the target object.

PIR sensors however are effective in detecting movements of humans or animals. These devices are made to ignore constant infrared sources such as ambient temperature and are specifically designed to detect rapid alterations in infrared levels within their detection range.

Pros of IR Sensor

  1. Has a versatile usage 
  2. Capable of measuring temperature apart from detecting objects
  3. Has control over emitted signal as it emits its own infrared radiation

Cons of IR Sensor

  1. Compared to PIR, IR is less effective in detecting motion
  2. Prone to disruption caused by ambient infrared sources

Pros of PIR Sensor

  1. Effective in detecting moving animals or human
  2. Reduced false positive as it focuses on sudden changes in infrared radiation
  3. Energy saving as it only activates when it detects motion

Cons of PIR Sensor

  1. It has limited application compared to IR because it primarily focus of movement detection
  2. PIR sensor is incapable of differentiating between different objects hence potential false positive alarm
  • Applications

IR Sensor

IR sensor has a wide application including:

  1. Measurement of temperature in various industrial processes
  2. Communication in remote control and IR information transmission 
  3. Detection of objects in automation frameworks

PIR Sensor

These sensors have a wide application only in fields that require motion detection, for instance:

  1. Security frameworks for homes and businesses
  2. Optimization of energy consumption in commercial buildings i.e., HVAC systems.
  3. Automatic lighting in homes and public spaces
  • Installation and Placement

IR sensors` installation appears more complex due to the fact that they emit their own infrared radiation. This might mean that they are carefully installed in areas where there are no other sources of infrared light at all to avoid possible interference.

On the other hand, PIR sensors are simple to install being that they don`t emit infrared light, instead, they passively detect alterations in infrared radiation. However, their placement should be carefully considered away from obstructions such as walls.

What Can Trigger a PIR Sensor?

PIR sensors have really transformed the realm of motion detection technology. The device offers unmatched efficiency in several applications. They detect motion by sensing alteration in the infrared light emitted by moving objects and living things. So below, let`s find out what triggers a PIR sensor:

  • Presence of Human Being

Human being is one of the main targets of PIR sensors. It detects the presence of human being by detecting the heat energy emitted by human, hence are ideal for smart home applications and security light systems.

  • Pet Movement

PIR sensors can also detect pets` movement. This can be advantageous, particularly for homeowners who want to keep an eye on their fuzzy companions. 

  • Environmental Factors

PIR sensors can sometimes be triggered by environmental changes such as rapid change in temperature as it is designed to respond to sudden changes in infrared radiation caused by temperature variations. Even though environmental triggers and usually predictable, rapid changes in the environmental temperature can lead to false positives.

  • Moving Objects

PIR sensors can also detect moving objects such as a door opening. Hence this ability extends their application beyond security. They can be used to customize settings for certain systems such as automatically opening a door when they detect a movement towards that particular door.

  • False Alarm

Although PIR sensors are designed to be very precise, a few factors can cause potential false alarms to these devices. For example, sudden change in temperature, presence of a reflective surface, or change in light hence triggering a false alarm. 

  • Limited Sensing Angle

PIR sensors have limited sensing angles hence interfering with their effectiveness. As a result, you should strategically position these devices to ensure utmost functionality and comprehensive coverage.

Is PIR Better Than Motion Detection?

When it comes to security technology, PIR sensor, and Motion Detection have emerged as the frontrunners for imposition detection frameworks.

Both devices hold their unique capabilities in the realm of security technology and other domains where they have wide applications. Therefore, you might be wondering… Is PIR Better Than Motion Detection? Let`s find out below.

PIR Technology

Harnessing Infrared Waves: PIR sensor excels in detecting infrared heat radiated by warm bodies like animals and human beings. PIR sensor`s passive approach guarantees minimal interference with the environment, hence making them suitable for both indoor and outdoor applications.

Outstanding Sensitivity: PIR sensor is capable of detecting even the faintest temperature alteration, hence differentiating between actual threats and potential false alerts that can be triggered by environmental factors.

Zoning Advantage: PIR sensors can allow the division of spaces into detection zones hence utmost and more precise monitoring reducing chances of missed intrusions.

Motion Detection

All-including Surveillance: motion detection frameworks are based on a number of technologies, encompassing microwave, video-based, and, ultrasonic sensors. As a result, motion detection offers an all-inclusive approach to intrusion detection. Due to their versatility, they have wide use in both homes and commercial applications.

Dynamic sensing: motion detection systems are suitable in areas where varying motion patterns need to be captured. This is because, unlike the PIR sensors, motion detection systems can sense a wide range of movements.

False Alarm Mitigation: by adopting advanced algorithms and multiple sensing techniques, motion detection systems have made significant advancements in minimizing false positives, hence ensuring utmost accuracy.

Comparative Analysis

Precision: PIR sensors work better in situations where precision and isolate detection are vital. PIR sensors` ability to solely focus on temperature alterations and neglect background movement makes them more accurate in controlled spaces.

False Alarm Challenge: Although motion detection systems are versatile, they have generally struggled with false alarms triggered by substances such as wind-blown debris, small animals, or even changes in light. However, advancements in sensor fusion and signal processing have significantly reduced this issue.

Environment and Application Dependency: PIR sensors are very sensitive to heat changes and therefore can be effective in detecting warm-blooded intruders, however, they can hesitate in environments with extreme fluctuation in temperatures. Motion detection systems on the other hand can effectively function well in a wide range of environments and threat scenarios.

Real-World Applications

  • PIR Brilliance: PIR sensors are suitable for indoor applications such as in homes, warehouses, and offices where consistent temperature variances can be expected. Its unmatched accuracy is vital for securing entry points and high-value areas.
  • Motion Detection Mastery: motion detection systems have the utmost capability of working in areas with high movement patterns. For example, you can consider installing them in areas such as bustling retail spaces and outdoor perimeters. This accuracy is aided by its adaptability to a number of sensor types allowing it to detect and 

differentiate several movements.

Note: In this era of integration and collaboration, security experts are beginning to merge the unique features of both PIR sensors and motion detection systems technologies to come up with hybrid systems. These hybrid systems deliver comprehensive intrusion detection that reduces the limitations of each approach.

What Can Block a PIR Sensor?

PIR sensors are designed to detect objects based on the fluctuation in infrared radiation the objects emit within their field of view. This feature has made PIR sensors vital assets in several applications. However, just like any other technology, PIR sensors are not impermeable to potential obstructions that might interfere with their performance. So, let`s see below, what things can block a PIR sensor.

  • Physical Obstructions

PIR sensors can be blocked by physical obstructions such as walls, doors, or furniture. These barriers block the line of sight between the PIR sensor and the monitored space hence, significantly reducing the sensors` ability to detect infrared radiation from nearby moving objects. As a result, you should ensure a legitimate sensor placement as well as coverage optimization to reduce such issues.

  • Extreme Temperatures 

PIR sensors generally depend on detecting temperature differences between the target object and their surrounding. Extreme ambient temperatures might mask temperature differentials, hence, leading to potential false positives. Ensure to calibrate the sensor`s sensitivity depends on the environment to reduce this challenge. 

  • Window Interference

Sometimes, your PIR sensor can be blocked from working properly by light from windows especially those having reflective coatings. When light strikes such surfaces, it can bounce infrared radiation hence confusing your PIR sensor.

This challenge can be reduced by carefully adjusting the sensor`s viewing angle away from windows and reflective surfaces. Or else, you can use curtains to cover your windows to reduce reflection.

  • Pet Movement 

Household pets also sometimes trigger PIR sensors and this might cause potential false alarms. However, there are some advanced PIR sensor such as pet immune technology that differentiates small heat emission hence only human movement is detected.

  • Sunlight and Glare

PIR sensor might also be blocked from working properly by glare which tends to saturate the sensor with infrared radiation. As a result, it might be difficult for PIR sensor to distinguish additional heat emission. This challenge can be reduced by opting for sensor anti-glare features. You can as well position your PIR sensor to avoid direct sunlight.

  • Height and Angle

Ensure you mount your PIR sensors at an appropriate height and angle to avoid blockage by elements that might reduce their workability. It is advisable to place your PIR sensor 6 to 8 feet above the ground to avoid the possible effects of terrestrial radiation. Slightly tilt your PIR sensor downwards for optimal coverage.

  • Heat Sources

Do not place your PIR sensor near heat sources of electronics as most of them emit heat while in constant use. When PIR sensors are exposed to heat, they become blocked from sensing the actual movement, thus ensuring you keep yours from electronics and heat sources. In this way, you can minimize potential false alarms.


PIR sensors are advanced devices that detect motion by sensing the infrared radiation emitted by objects within their range. So you might want to know…

How PIR Sensor Works.

The difference between the surrounding heat and the heat radiation emitted by objects such as animals and human beings is what triggers a PIR sensor. These sensors have wide application in the security sector among other fields. 

Although PIR sensors also have a few disadvantages, among their advantages is; energy efficiency. They are energy efficient as they stay off and are activated only when they detect an object within their range. Secondly, they need minimal maintenance and have a lifespan of between 4 to 7 years.

On the other hand, the PIR sensor`s reliance on heat to detect motion can sometimes be interfered with hence causing false positives. As a result, these sensors should be kept away from objects that might generate heat while in use such as some electronic, or heat sources like heaters.

IR is another device in the field of motion detection, however, IR and PIR differ in how they sense motion, and as a result, IR has a wider application than PIR. PIR sensor responds to a difference in infrared radiation while IR responds to any type of infrared radiation. 

Triggers for PIR sensors might include heat, hence they are responsive to humans and animals. However, PIR sensors might not detect non-heating objects or in some cases, extreme cold or hot temperatures might hinder their ability to detect objects. Compared to IR motion detection systems, PIR excels in a specific application while IR has the ability to detect any infrared radiation and has numerous applications.

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