Types of Sensor
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The document discusses various types of non-contact sensors, including proximity, infrared (IR), ultrasonic, light, and smoke & gas sensors, explaining their principles and applications. Proximity sensors detect objects without contact, whereas IR sensors, which are common in mobile phones, use light for object detection. Ultrasonic sensors measure distance and velocity by using sound waves, and smoke & gas sensors are crucial for safety in various environments.
Types of Sensor
- 1. Proximity sensor is a type of non-contact sensor used for object detection. It does not have any physical contact with the object. The object whose distance is to be measured is known as target. An IR light or electromagnetic radiation is used in a proximity sensor. There are different types of proximity sensors like Inductive, capacitive, Ultrasonic, etc. applications: Object detection, to measure velocity, rotation identification, material detection, Reverse parking sensor, object counting. Proximity Sensor Mohammad Mujtabir Israil Kaif, Rajshahi Reference: Electronics Hub
- 2. IR Sensors or Infrared Sensor are light based sensor that are used in various applications like Proximity and Object Detection. IR Sensors are used as proximity sensors in almost all mobile phones. There are two types of Infrared or IR Sensors: Transmissive Type and Reflective Type. In Transmissive Type IR Sensor, the IR Transmitter (usually an IR LED) and the IR Detector (usually a Photo Diode) are positioned facing each other so that when an object passes between them, the sensor detects the object. The other type of IR Sensor is a Reflective Type IR Sensor. In this, the transmitter and the detector are positioned adjacent to each other facing the object. When an object comes in front of the sensor, the infrared light from the IR Transmitter is reflected from the object and is detected by the IR Receiver and thus the sensor detects the object. Infrared Sensor (IR Sensor) Mohammad Mujtabir Israil Kaif, Rajshahi Reference: Electronics Hub
- 3. An Ultrasonic Sensor is a non-contact type device that can be used to measure distance as well as velocity of an object. An Ultrasonic Sensor works based on the properties of the sound waves with frequency greater than that of the human audible range. Using the time of flight of the sound wave, an Ultrasonic Sensor can measure the distance of the object (similar to SONAR). The Doppler Shift property of the sound wave is used to measure the velocity of an object. Ultrasonic Sensor Mohammad Mujtabir Israil Kaif, Rajshahi Reference: Electronics Hub
- 4. Sometimes also known as Photo Sensors, Light Sensors are one of the important sensors. A simple Light Sensor available today is the Light Dependent Resistor or LDR. The property of LDR is that its resistance is inversely proportional to the intensity of the ambient light i.e., when the intensity of light increases, its resistance decreases and vise-versa. By using LDR is a circuit, we can calibrate the changes in its resistance to measure the intensity of Light. There are two other Light Sensors (or Photo Sensors) which are often used in complex electronic system design. They are Photo Diode and Photo Transistor. All these are Analog Sensors. There are also Digital Light Sensors like BH1750, TSL2561, etc., which can calculate intensity of light and provide a digital equivalent value. Light Sensor Mohammad Mujtabir Israil Kaif, Rajshahi Reference: Electronics Hub
- 5. One of the very useful sensors in safety related applications are Smoke and Gas Sensors. Almost all offices and industries are equipped with several smoke detectors, which detect any smoke (due to fire) and sound an alarm. Gas Sensors are more common in laboratories, large scale kitchens and industries. They can detect different gases like LPG, Propane, Butane, Methane (CH4), etc. Now-a-days, smoke sensors (which often can detect smoke as well gas) are also installed in most homes as a safety measure. The “MQ” series of sensors are a bunch of cheap sensors for detecting CO, CO2, CH4, Alcohol, Propane, Butane, LPG etc. You can use these sensors to build your own Smoke Sensor Application. Smoke & Gas Sensor Mohammad Mujtabir Israil Kaif, Rajshahi Reference: Electronics Hub