Physical security and safety have always been critical to the welfare of individuals, families, businesses, and societies—think of the Great Wall of China, your front door's lock, or the sophisticated security system in a prison.
Modern Security Technology: 5 Types of Security Sensors
The Internet of Things (IoT) has enabled growth in the residential and commercial security industries, but IoT security technology relies heavily on the sensors that power these solutions. Let's explore five common sensors in modern residential and commercial security applications.
1. Infrared (IR) Security Sensors
Infrared sensors utilize infrared light to detect motion. In a security system, that motion triggers an alarm, turns on lights, or sends an alert. There are, however, two different types of infrared sensors commonly used in security devices ― active and passive infrared sensors.
· Active infrared (IR) sensors utilize an emitter and receiver to monitor the distance from an object to a sensor. The emitter first shines an infrared light on an object. As the object moves, the receiver can gauge the distance between the object and itself. Active IR sensors are used for obstacle avoidance in robotics and automotive settings, but you can find them in security applications such as proximity detection for fine artwork or jewelry.
· Passive infrared (PIR) sensors contain only an infrared receiver that "sees" the infrared light an object ― such as a human, animal, or dangerously overheating server ― emits. PIR sensors are more common than active IR sensors in security devices because they require lower power and less supporting hardware, and because they are better adapted for security settings.
2. Photoelectric Beams
Photoelectric sensors may be more common in spy films than real life, but you can find them at work in specific security settings. Photoelectric sensors would be helpful in, for example, an environment that contains a space humans or objects may not enter.
Like PIR and active IR sensors, photoelectric beams use invisible IR light. But photoelectric beams can travel significantly farther than PIR and IR sensors because the emitter source is focused through a lens and transmitted to a distant receiver up to 100 meters away. Photoelectric beams establish an invisible barrier that, when broken, triggers a security notification. One downside is that photoelectric beams are more prone to accidental alarms if, for instance, a leaf falls through the beam, the ambient temperature gets too hot, or something interrupts the emitter and receiver's alignment.
3. Microwave Sensors
Like active IR sensors, microwave sensors emit and receive a signal to detect an object in motion. Microwave radiation has its advantages and disadvantages, but these sensors are generally much more sensitive than infrared sensors. This sensitivity can be highly advantageous but can also result in false alarms ― triggered by small environmental movements like trees blowing in the wind or curtains shifting in a breeze. Unlike IR sensors, microwave sensors can sense motion through non-metal materials like wood, plastic, and drywall. Additionally, microwave sensors are more durable than IR sensors, making them suitable for outdoor or constant-use applications. Microwave sensors require more power than infrared motion sensors to operate, but have higher sensitivity and a greater ability to sense motion at long distances.
4. Tomographic Motion Detection Sensor
Unlike the other security sensors we've covered so far, tomographic motion technology does not require a direct line-of-sight to trigger a security warning. Relatively new and still proprietary, tomographic motion detection utilizes a mesh network of radio emitters and receivers to detect any motion within the mesh network. This sensor technology works by detecting interruptions in signals between emitters and receivers, which it interprets as motion. Tomographic motion has only been around for about a decade, but it's a promising technology for high-security commercial and industrial sectors.
5. Microphones
Most security sensors rely on the electromagnetic spectrum to trigger warnings, but microphones rely on the audio spectrum. Don't sell microphone technology short ― these sensors have much more subtle detection capacity than just the sounds humans can hear.
For example, breaking glass emits specific bands of ultrasonic frequencies that the human ear cannot perceive. Microphone sensors can detect these inaudible frequencies and trigger alerts and alarms. Microphones have an extremely versatile sensing ability and are less limited to line-of-sight use than electromagnetic-based sensors. However, they are also more dependent on peripheral hardware ― and complex software ― to support processing the signals the microphones produce.
Conclusion
Sensors make up a massive portion of the technology behind modern security systems. As processing power and software capabilities continue to increase, sensor network complexity and capacity will follow in stride.
