Types of Sensors
Light Sensor
The light sensor detects the amount of light.
Applications
Light sensors can be used to monitor the amount of light present in a green house.
It may be used to detect presence of a person at an entrance.
It also used in automatic street lighting system.
Temperature Sensor
A temperature sensor is a device, typically, a thermocouple or RTD (Resistance Temperature
Detectors) that provides for temperature measurement through electrical signal.
Applications
It can be used to monitor temperature in a room/ green house; Heating/cooling system like an
air conditioner, washing machine.
Magnetic fields sensor
It is proximity sensor that uses a combination of a reed switch and a magnet to detect the
presence of a magnetic field.
Magnetic sensors are used for the detection of positions without contact or wear and tear in
control technology.
For example, in an automatic gate system, the magnetic sensor only detects the magnet
which is to be detected.
Gas Sensor
An example of a gas sensor is the oxygen Gas sensor. It can be used to monitor gaseous
oxygen levels in a variety of biology and chemistry experiments.
The sensor is intended for measuring oxygen concentration.
The use of gas sensor can help for pollution control and for the development of car exhaust
devices.
Moisture Sensor
They detect dampness or dryness. Humidity is the presence of water in air.
Humidity measurement in industries is critical because it may affect the business cost of the
product and the health and safety of the personnel.
Hence, humidity sensing is very important, especially in the control systems for industrial
processes and human comfort.
Applications
Automatic greenhouses, Environmental monitoring, Agriculture, factories that manufacture
items that can be ruined by too much air moisture.
Pressure Sensor
Pressure sensors can be used to measure force and determine the presence of a person or
object. It may detect if force is applied on a object, for example pressing a button.
Applications
Burglar alarm systems, Washing machines, robotics, environmental monitoring.
Detecting cars arriving at a car park barrier/ traffic light.
pH Sensor
It is used to measure acidity or alkalinity. For example, a pH sensor can be used to measure
hydrogen ion concentration of a solution. The greater the hydrogen ion concentration, the
smaller the pH; when the pH is above 7, the solution is basic that is alkaline and when it is
below 7, the solution is acidic.
Applications
Automatic greenhouses, chemical manufacturing, environmental monitoring, Monitoring
River pollution.
Motion/ Infrared sensor
The motion sensor is an infrared human detection sensor. It is designed to be incorporated
into various devices that exist around us in daily life.
Applications
Burglar alarm system, Automatic door.
Exercise
What is the purpose of sensors in a monitoring and control system?
Describe two sensors that can be used in burglar alarm system.
Match the sensors with the appropriate possible applications provided
Temperature
Moisture
Oxygen
Light
Infrared
Pressure
Acoustic
Motion
pH
Applications
Detecting an intruder by breaking an infrared beam
Used in controlling central heating systems
Detecting liquids moving in pipes (chemical processes)
Detecting speed (e.g., radar guns measuring vehicle speed)
Measuring oxygen content in a river to check for pollution.
Used in green houses to monitor soil acidity.
On automatic doors to detect the presence of a person
Detecting intruders in a burglar alarm system
Check moisture level in the production of tablets in pharmaceutical company