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Security sensors basics | Types of Security sensors, working

This article covers Security sensors basics and types of Security sensors including their applications. It describes working operation of different types of Security sensors viz. motion sensors, Ultrasonic sensor, Tomographic sensors, wireless sensors, chemical sensors, magnetic sensors etc.

Introduction:
Due to advancement in technology, threats and vulnerabilities to human lives are increasing. Moreover crime rates are increasing. People feel unsafe unless there are adequate security systems available. Electronic security sensors play critical role in such security systems. We are aware of CCTV surveillance systems. In this article we will go through sensors and systems other than CCTV used for various security applications such as national security, home security, personal security, industrial security and cybersecurity.

What are Security sensors and their applications?

• The sensors used for security applications are known as security sensors.
• For national security radar, satellite, UAVs (Unmanned Aerial Vehicles), security robots, Electro-optical sensors are used.
• For home security motion sensors and CCTVs are used.
• For personal security panic alarms, child locators, mobile SOS buttons, implantable microchips etc. are used.
• For industrial security fire alarms, chemical sensors, access control systems (based on RFID, NFC, biometric etc.), video surveillance systems, intrusion detection systems etc. are used.
• AI (Artificial Intelligence) packed with sensors and ML (Machine Learning) techniques are used in cyber security to minimize data theft and other malicious activities.

Working operation of different types of Security Sensors

Following are the types of Security Sensors based on their construction and working operation. Motion sensors use infrared, ultrasonic or radio frequency for their operation as described below.

Motion Sensors using microwave frequency or infrared frequency

PIR sensor

• Motion sensors are classified into two types viz. active and passive. These sensors trigger alarm when they detect human beings or animals. Motion sensors are usually installed outside the house. These sensors sense movement of someone walking around your house or premise and alert the owner or concerned security team.
• Active motion sensor emits radio frequency in the microwave region and will analyze the returned/reflected microwave frequency for determining motion. They are known as microwave motion sensor.
• Human or animal body radiates energy in the form of infrared radiation. Hence when human/animal come in the range of passive motion sensor, the sensor receives thermal energy and hence motion is detected by the sensor. It is also known as PIR (Passive Infrared) sensor.
➨Refer motion sensor basics and types >> and Active vs Passive motion sensors >>.

Ultrasonic Sensors used as motion sensors

Ultrasonic sensor

• These sensors use ultrasonic frequency waves for their operation.
• The sensor consists of two parts viz. transmitter and receiver. The transmitter part converts electrical energy into sound and transmits it. The receiver part receives the echo and turn this received sound waves into electrical energy to determine distance of the object from the ultrasonic sensor. Hence it is also known as distance sensor.
• Ultrasonic waves fall above the normal range of human beings but animals can hear these waves. Hence transmission of ultrasonic frequencies keep animals away from the area to be protected by such types of security sensors.
➨Refer Ultrasonic sensor basics and working >>.

Tomographic sensors used as motion sensors

These sensors work on radio frequencies. This sensor emits radio frequency waves and sense disturbances to these radio waves as they pass between nodes of a mesh network. They can penetrate through walls and other obstructions and hence can work efficiently over larger coverage areas. These sensors are very useful for warehouses and large storage areas.

Wireless sensors

Wireless sensors use wireless standards such as RFID, wifi, bluetooth, NFC, zigbee, zwave etc. for their operation. These sensors use one or more of these standards for communication. The security systems designed using wireless sensors are known as smart security systems. Such systems are monitored and controlled using applications installed on smartphones. These apps can monitor doors, windows, surveillance cameras, lights, smoke, sirens etc.
➨Refer different types of Wireless sensors >> for more information.

Chemical sensors

• It is a device which transforms chemical information (such as composition, element/ion presence, concentration, partial pressure, chemical activity etc.) into an analytically useful signal.
• Chemical sensors contain two components which are connected in series viz. chemical (molecular) recognition system (i.e. receptor) and physicochemical transducer. In major chemical sensors, the receptor interacts with analyte molecules.
• These sensors are used in various fields such as medicine, environmental pollution, home safety and so on.
• They are also used to detect organic compounds present in gases.
• Some of these chemical sensors find different applications such as radio frequency detection, sensing toxic materials, toxic vapors, bomb detection, chemical agent simulants etc.
• The ideal chemical sensor is inexpensive, portable and foolproof device

Magnetic sensors

• Magnetic sensors are classified based on their measurement. It depends whether they measure magnetic flux density in specific direction or they measure total strength of a magnetic field.
• They are used for the detection of ferromagnetic and conducting objects, navigation, position tracking, linear/angular position and rotation sensing and in anti-theft systems.
• Magnetic sensors are developed based on various technologies such as coil, fluxgate, SQUID, hall effect, optically pumped, nuclear precession, giant magneto-resistance, anisotropic magneto resistance, giant magneto impedance, piezoelectric composites etc.
➨Refer Magnetometer basics and types >>.

Other Security sensor types

Following are other types of security sensors or systems used for providing security at various levels to human beings.
• Biometric access control systems such as gesture detector, fingerprint sensor, face recognition systems etc.
• RFID based proximity access systems normally used in offices, factories, banks, government establishments and so on.
• Use of implantable microchips in livestock allows farmers to track their animals. They are also used by parents requiring safety of their children. These microchips are implanted in the human body, which provides informations such as location etc. which help in tracking the children or human beings.



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