Definition of Sensors and Types of Sensor

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One Electronic components which is often used in a circuit is a Sensor. Devices that have various types and functions you can get easily on the market.

There are many types of sensors, including light sensors, pressure, accelerators, temperature, sound, distance, water humidity, and many others. Check out this article well to know the details of the review.

Definition of Sensor


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What is Sensor? According to KBBI, the definition of a sensor is a device that can detect the possibility of changes in physical quantities, namely in the form of force, pressure, movement, light, temperature, humidity, speed, electrical quantities, and other phenomena.

According to the journal reported from the lecturer website  , sensor output is usually in the form of a signal that is converted into a human-readable display at the sensor location or transmitted electronically through the network for further reading or processing.

When certain changes occur, the input will be converted to output that can be understood by humans. There are various kinds of sensors, including the following explanation.

Sensor Classification


A sensor has different characteristics and uses. The division of sensor variants itself is divided into 4 types of variants, including active sensors, passive sensors, digital sensors, and also analog sensors. You can see the detailed explanation below:

Sensor Type Based on Working Principle

  • Active Sensor

Active sensors are radar instruments used to measure signals transmitted by sensors reflected, refracted, or dissipated by the surface of an object.

Unlike passive sensors, the working principle of this active sensor requires an external power source to carry out its operation. The working principle of the active sensor is to emit energy pulses and detect the reflected energy.

One example of a device that uses an active sensor is an X-ray machine. An x-ray machine sends energy into your body and measures what is reflected back to the sensor by structures resistant to that wavelength, such as bone.

  • Passive Sensor

The definition of a passive sensor is the opposite of an active sensor. Passive sensors are types of sensors that in operation do not require additional external power sources, whether in the form of Power And electric current.

Simply put, the definition of passive sensors is a device that detects and responds to some type of input from physical objects around it. Passive sensors can only be used to detect energy when natural energy is available.

Sensor Type Based on Output Type

  • Digital Sensors

A digital sensor is a device whose signal output value is directly converted into a signal in digital form. Signals are usually measured in two states in digital sensors: on and off.

An example of the use of digital sensors can be seen in door sensors that provide output in two circumstances, either usually closed (NC) when the door is open or usually open (NO) when the door is closed.

  • Sensor Analog

An analog sensor is a device that produces analog output according to a calculated quantity. This sensor also works by observing changes in external factors that exist around it.

The working principle of analog sensors is to use external parameters around them, such as wind speed, solar radiation, light intensity, etc. which will later provide analog voltage as output.

Sensor Type According to Structure and Features:

A sensor is classified according to their structure and features. Among the variants of sensor variants based on structure and features are:

  1. Sensor-Based Output: Differential output,  Resistive output, voltage output etc.
  2. Sensor Based Sensing Parameters: Temperature, Light, pressor etc.
  3. Application Based Sensors:  Automotive Sensors, Industrial Sensors etc.

Types of Sensor


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  • Sensor Proximity

Proximity sensors or often also known as proximity sensors are non-contact type sensors that detect the presence of a nearby object.

This proximity sensor can be implemented using techniques that do not require direct contact with objects, such as Optics (for example such as the use of Infrared or Laser light), Sound (Ultrasonic), Magnetic (Hall Effect), Capacitive, and so on.

Some examples of the use of proximity sensors that we often encounter for example on Infrared and barcode scanners on our Smartphones, car parking sensors, industry (object alignment), and also on Ground Proximity on Aircraft.

  • Light Sensor

Light Sensor or Light Sensor is an analog sensor used to detect the amount of light that hits the sensor. These analog light sensors can be further classified into several types such as photo-resistors, Cadmium Sulfide (CdS), and photocells.

Light dependent resistors or LDRs can be used as analog light sensors that can be used to turn loads on and off automatically based on the intensity of light they receive.

LDR resistance increases as light intensity decreases. Conversely, LDT resistance will decrease as the intensity of light received increases.

Read also Definition of Light Sensor and Circuit Examples

  • Temperature Sensor

Temperature sensors are widely available sensors in both digital and analog sensor form. There are different types of temperature sensors used for different applications.

One of the Temperature Sensors is the Thermistor, which is a thermally sensitive resistor used to detect temperature changes. As the temperature increases, the electrical resistance of the thermistor increases as well. Conversely, if the temperature decreases, then the resistance will also decrease.

Another example of the use of a temperature sensor is on a thermometer. In mercury-based glass thermometers, the input is temperature. The contained liquid expands and shrinks in response, causing levels to become higher or lower on the marked gauge, which humans can read.

  • Ultrasonic Sensor

Ultrasonic sensors are a type of non-contact sensor that can be used to measure the distance as well as speed of an object. Ultrasonic sensors work based on the properties of sound waves with frequencies greater than the range of the human voice.

Using sound waves, ultrasonic sensors can measure the distance of an object (similar to SONAR). The Doppler properties of sound waves can be used to measure the speed of an object.

  • Pressure Sensor

The working principle of this pressure sensor is to convert mechanical voltage into electrical signals. The lack of tension is based on the principle that the introductory prisoner changes with the length and cross-sectional area. The force exerted on the wire causes the wire to bend, causing the size of the wire to change and change its resistance

  • Acceleromator Sensor

Accelerometer sensors are sensors that detect changes in position, speed, orientation, shock, vibration, and tilt with sensory movements. These analog accelerometers can be further classified into several different ones based on variations, configurations, and sensitivities.

Based on the output signal, analog Accelerometers produce a constant variable voltage based on the amount of acceleration applied to the Accelerometer. In addition to Analog Accelerometers, these Accelerometers are also digital.

  • Oxygen Sensor

One example of the use of oxygen sensors (oxygen sensor) you can see in the car’s emission control system detects the gasoline / oxygen ratio, usually through a chemical reaction that produces voltage. The computer in the machine reads the voltage and, if the mixture is not optimal, readjusts the balance.

  • Sound Sensor

A sound sensor is an analog sensor used to sense sound levels. This analog sound sensor translates the amplitude of the acoustic volume of the sound into electrical voltage to sense the sound level. This process requires multiple circuits, and uses a microcontroller along with a microphone to produce an analog output signal.

  • Proximity Sensor

Proximity Sensor or commonly referred to in English also Proximity sensor or can also be called Sensor For Displacement, Distance and Position is a sensor designed to detect the presence of objects without physical contact.

The sensor is quite an important component of its existence. Proximity sensors have electromagnetic beams of electromagnetic radiation (infrared, for example). It can also be said that the Proximity Sensor is a device that can convert information about the movement or presence of objects into electrical signals.

  • Motion Sensor

The easiest example of using motion sensors can be seen in home security lights, automatic doors, and bathroom fixtures usually transmit some type of energy, such as microwaves, ultrasonic waves, or light rays and detect when the flow of energy is interrupted by something entering its path.

  • Humidity Sensor

Humidity Sensor or Humidity Sensor is a sensor used to detect the humidity level of a location. Humidity Level measurement is very important for environmental observation in an area, medical diagnosis or in the storage of sensitive products.

If you look at Weather Monitoring Systems, they often provide temperature as well as humidity data. So, measuring humidity is an important task in many applications and Humidity Sensor helps us achieve it.

  • Color Sensor

Color Sensor is a useful device in building color sensing applications in the field of image processing, color identification, industrial object tracking, etc.

One of the most commonly used examples of color sensors is the TCS3200 type. This type of color sensor is a simple color sensor that can detect any color and produce square waves proportional to the wavelength of the detected color.

  • Tilt Sensor

Tilt sensors or often known as Tilt Sensors are devices used to detect tilt or orientation.

The Tilt Sensor is one of the simplest and cheapest sensors out there. Previously, tilt sensors consisted of Mercury (and hence were sometimes referred to as Mercury Switches) but most modern tilt sensors contain roller balls.

  • Water Sensor

Water sensor or water level is a set of tools used to measure water levels in different places in order to obtain comparative knowledge.

The simplest water level is a pair of pipes that access each other on the lower member. A simple water level measures the water level through the water level in the 2 pipes whether similar or not.

Currently, water levels can be measured easily using modern tools such as Water Level. Understanding Water Level itself is a set of tools used to measure water levels in different places in order to obtain comparative knowledge.

The simplest water level is a pair of pipes that access each other on the lower member. Simple water level will measure the water level through the water level in the 2 pipes whether similar or not.

The measurement results from the water level are lower than using a laser but the water level has high accuracy in long-distance measurements. To avoid measurement errors in the use of water levels, the temperature of the water must be the same.

  • Hall Effect Sensor

Hall Effect Sensor is a sensor that can convert magnetic information into electrical signals for processing electronic circuit Next.

This Hall Effect Sensor is often used as a sensor to detect proximity (proximity), detect position (positioning), detect speed (speed), detect directional movement (directional) and detect electric current (current sensing).

  • Smoke and Gas Sensor

One sensor that is often used in room security system applications is the Smoke and Gas Sensor. Almost all offices and industries are equipped with several smoke detectors, which detect the presence of smoke (due to fire) and sound the alarm.

Gas sensors are more common in laboratories, large-scale kitchens and the hospitality industry. They can detect different gases such as LPG, Propane, Butane, Methane (CH4), etc.

  • Alcohol Sensor

As stated in the name, Alcohol sensors or Alcohol sensors are devices that are able to detect the amount of alcohol in objects and humans.

Typically, alcohol sensors are used in breathalyzer devices, which determine whether a person is drunk or not. Law enforcement personnel use breathalyzers to catch drunk offenders and driving.

The sensor is a part that you need to pay attention to in every component of electronic equipment, because it affects the performance of the equipment. By knowing the type, you can find out how the application of each existing sensor.

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