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Home Latest Articles Smartphones Kagoo Explains: Introduction to Smartphone Sensors

Kagoo Explains: Introduction to Smartphone Sensors

Updated 15 April 2021
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Kagoo recently started supporting smartphones on the site, offering comprehensive details on a whole range of quality smartphones. You can browse all the latest Smartphones in our Smartphone Hub & view the best deals on our Smartphone Deals Page. To celebrate their arrival, we’re looking in depth at smartphone features - today we’ll be looking at some of the key technology hiding under the hood of your phone.

Smartphones are - as the name would suggest - smart gadgets. This doesn’t mean they deconstruct postmodernism or argue about Proust: it means they have the capability to collect, analyse & share data to function more efficiently & make your life easier. Smart technology is built around two primary technologies - sensors and wireless connectivity. Today we’re going to give an introduction to the main sensors powering your smartphone.

What is a sensor?

A sensor is simply a device which can detect a physical stimulus and create a digital signal in response. For example: when you burn toast in the morning, the sensor in your smoke alarm will detect the smoke, and transmit a signal to activate the alarm.

Sensors are a very broad classification, and there is a huge number of things an individual sensor can measure. However the sensors inside smartphones can be broken down into 3 main categories:

  • Motion
  • Environmental
  • Positional

As the name suggests, motion sensors detect movement. This is largely related to the phone itself (i.e - how fast the device is moving, when it’s being rotated) rather than foreign objects. Environmental sensors on the other hand largely measure the surrounding area - such as temperature or humidity. Finally positional sensors detect where the device is right now.

You also have biometric sensors - these detect & measure the unique elements in each human body, and are used to identify one person from another. They are most commonly used for security & access control inside smartphones.

Let’s now take a closer look at some of the most common smartphone sensors inside these categories:

Accelerometer: This sensor is designed to measure acceleration - how fast the phone is moving at a given moment. The most prominent use of an accelerometer is in step tracking - it allows the phone to detect your movement, which it can translate into steps, even without wearing a dedicated pedometer. They can also be used for image & video stabilization, maps & positioning systems.

Gravity Sensor: A special type of accelerometer, a gravity sensor only measures the effect of gravity on the device, while an accelerometer measures all forces acting on the phone. Sometimes these are discrete devices, sometimes the gravity sensor merely takes the full data from the accelerometer and filters out everything it doesn’t need.


Gyroscope: A gyroscope detects tilting and orientation changes as you turn your phone, or change from portrait to landscape. It’s used for numerous functions, such as auto-rotating videos when you turn your phone, detecting which way you’re facing, and tilt/movement controls in apps (such as turning the phone to steer a racing game).

Magnetometer: The magnetometer is designed to detect geomagnetic fields. By measuring the strength of these fields, it can work out which direction is magnetic north - allowing it to know which direction your phone is pointing. This is used by itself in compass apps, but is mostly used as part of the GPS and maps system to work out your exact position.

GPS: The Global Positioning System (GPS) is both a system and a sensor. As a sensor, it pings the 27 satellites in orbit above us, and measures the speed of their response to triangulate a rough position. As a system, it uses this data alongside the accelerometer, gyroscope, magnetometer - as well as using data from cellular towers - to precisely pinpoint the exact location of your phone.

Microphone: The microphone, unsurprisingly, detects sound - measuring how loud it is, capturing it and digitising it for use by other applications. It is most clearly used in the ‘phone’ part of a smartphone, but is also used for voice commands to personal assistants (Siri, Alexa et al), noise cancelling on music, and much more.


Light Sensor: This sensor measures the amount of light falling onto it. There are numerous different applications for this data - many phones displays will utilise light sensors for automatic brightness adjustment, while camera apps can use it to tweak settings for the best image quality.

Proximity Sensor: A proximity sensor uses an infrared LED to detect how close another object is to the sensor. It is primarily used to detect when you put the phone to your ear to take a call, at which point it disables the screen to stop you accidentally activating something with your ear.

Depth Sensor: This is a sensor used for measuring depth - i.e how far away a number of objects are from the phone. It is more powerful than a proximity sensor, and designed to build up a ‘map’ of the immediate area by sending out a huge number of ‘pings’ from the phone and measuring the time of return - an idea similar to radar. This depth map can be used for 3D and bokeh effects with cameras, and is the key to effective Augmented Reality.

Temperature Sensor: As you might expect, a temperature sensor can detect how hot or cold something is. It can be used to measure the temperature both inside and outside the phone. An internal temperature sensor will detect if the device is running too hot, which could cause damage. An ambient (outside) temperature sensor is used for weather apps.

Humidity Sensor: This is a sensor for measuring the humidity of the surrounding area. As with the temperature sensor, it is primarily used for weather apps.

Barometer: A barometer measures atmospheric pressure. While rarely found inside smartphones, it can be used to detect changes in weather and calculate your current altitude.

Fingerprint Reader: A fingerprint sensor uses light or sound waves to detect the unique pattern of a human fingerprint. These are used for security systems on phones, locking the phone unless a recognised fingerprint is detected. There are numerous variations of fingerprint detection on phones - some as a dedicated button, some placed under the screen.

Facial Recognition: A more powerful method of biometric scanning, facial recognition can detect and measure a number of unique measurements in a human face, and use them to differentiate between people. While supposedly harder to spoof than fingerprint scanning, it requires good ambient light to function and doesn’t always work if you’re wearing certain accessories - such as masks, which is a trouble right now!

The exact configuration of sensors in your phone will vary massively depending on age, cost and manufacturer. Top-shelf handsets may have the majority crammed inside, while others rely on a cut-down selection. Either way, hopefully this has helped you better understand the technology hiding in your phone! You can check out the best smartphones and deals on our Smartphone Hub.

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