Sensors are everywhere and in almost everything used in transportation, manufacturing, homes, and offices. Even ordinary consumer products use sensors for converting physical parameters like distance, temperature, position, and object proximity.

What are sensors?

There are various definitions of sensors, but the simplest is defining a sensor as an input device which produces a corresponding output or signal with the physical property that needs measurement. In general, a sensor is only one part of a large system connected to the central processor. To further understand what a sensor is, take the following example into consideration.

One example of a sensor is a light dependent resistor. The device resistance varies depending on the light intensity the device is exposed to. When there is more light, the device produces less resistance, and when there is less light, the resistance increases.

Classifying sensors

Sensors also come in different classifications depending on the preferred technology of manufacturers. If you go to, you will see a wide variety of sensors manufactured using a non-contact inductive method. This is only one example of classifying a sensor.

Sensor classifications can be simple or complex. The following are common sensor classifications used in the industry today:

  • Active and passive sensors. Active sensors require an external power or signal source. On the other hand, passive sensors generate output without the need for an external power source.
  • Classification depending on the means of detection. Examples of sensor means of detection are chemical, biological, electrical, and radioactive.
  • Classification based on conversion phenomenon. This refers to the type of input and output. Specific examples of sensors classified according to conversion are electromagnetic, photoelectric, and thermoelectric.
  • Analogue and digital output. Digital sensors produce a discreet stream of digital pulses while an analogue sensor generates a continuous signal concerning the parameter being measured.

These classifications help design engineers narrow-down sensor selection for specific types of applications.

Examples of sensor types

Since you already have a basic knowledge of how sensors are classified, there are specific types of sensors commonly used today.

  • Proximity sensor
  • Touch sensor
  • Light sensor
  • Fluid flow sensor
  • Pressure gauge
  • Accelerometer
  • Temperature sensor
  • Ultrasonic transducer
  • Tilt sensor
  • Linear sensor
  • Angle sensor

The next part of this article expands on the descriptions of a few of these specific types of sensors.

Proximity sensor

This type of sensor uses non-contact sensing technology to detect object proximity. The most common application of a proximity sensor is in cars and mobile phones. This type of sensor is also used in aircraft and to align objects in industrial applications.

Temperature sensor

A temperature sensor measures temperature change and is also one of the most common and identifiable types of sensor. You can find temperature sensors in consumer products like phones, computers, cars, and HVAC systems.

Infrared sensor

Infrared sensors use light in the detection of object proximity. This type of sensor is also commonly used in mobile phones. Advanced infrared sensors are also applied in robotics, industrial machines, and cars.