Different Mobile Phone Sensors and How do they work?

Ever looked different sensors in Mobile Phone and got confused what job do a sensor performs? Your all doubts are being cleared now.

Sensors, As the name suggests, these components are used to sense something that existed physically i.e. Light Intensity, Mobile Orientation etc. and converts the information sensed into electrical signals which are sent to processor which acts upon the sensed data as needed. i.e. If Sensor detects you placed the mobile near your ear during call, the Display is automatically turned off to prevent unwanted touch gestures.

Sensors we will be learning about, below in the post, are:

Ambient Light Sensor

Used for – Automatic Screen Brightness Adjustment – The brightness lowers automatically when you enters dark and increases when you came out in lightning so that you can see the screen comfortably.

Working of Ambient Light Sensor – It is usually located on the top near the earpiece. It does the job of sensing the illumination of light in front of screen. What placed inside is a LDR, or a Light Dependent Resistor which changes its resistivity according to the intensity of light. In this way, the data is converted to digital foam and processor comes to know the intensity of light .

Touch Screen Sensor

Used for – Identifying touch gestures over the screen and makes processor to act upon it and show the required data on screen. If you are reading this post on the mobile, It is a touch screen mobile and these are your gestures which drags page up and down.

Working of Touch Screen Sensor – All mobiles have a touch screen sensor, we usually calls touch screen. It identifies the touch gestures on the screen. It have a lot of transparent wires, placed horizontally and vertically, when we touch at specific part of screen, our finger makes a resistance between the wires placed bidirectional, and the point is calculated.

Fingerprint Sensor

Used for – Authentication of ourselves using our finger to unlock the lock screen and some protected apps ans also for purchases.

Working of Fingerprint Sensor – It is very popular now a days in mobile phones. We can authenticate ourselves with our unique fingerprint using this sensor. These are of two types: Optical and Capacitive. Optical fingerprint sensor is very less used in the phones. It captures a high resolution picture of finger and scans for fingerprints and converts it to binary foam whereas Capacitive sensors works just like touch screens and have a large number of wires placed vertically and horizontally. The raised pores of our finger, while came in contact with the wires, Changes the resistance between wires and the processor comes to know the resistance between each wire and identifies us.

Proximity Sensor

Used For – Turning the screen off when call is going on and phone is placed near the ear to prevent unwanted touch gestures on the screen.

Working of Proximity Sensor – It can be physically seen near the camera on top in front side. What it does is throws an invisible infrared light in front and detects the amount of light coming back to sensor. When something is bought near the sensor, the invisible light reflects back to sensor. Calculating the intensity of reflected light, sensor comes to know much much near the object is.

Accelerometer Sensor

Used For – Detecting the orientation of phone in three axis i.e. Portrait, Landscape and rotating the inside screen contents accordingly when auto rotate is turned on.

Working of Accelerometer Sensor – What placed inside a piezoelectric accelerometer sensor is a small crystal of some mass attached by a spring. When we change the orientation of out device the crystal moves by gravitational force on it. The displacement of the crystal is tracked via capacitive and resistive techniques. Complete assemblies of such type of arrangement is placed for all three axis. Which are calculated by the processor and works accordingly.

Gyroscope Sensor

It is just a better and extended version of Accelerometer Sensor.

Used For – 360° Videos and Photos capturing and watching. Mainly used in Virtual Reality and playing mobile games.

Working of Gyroscope Sensors – It adds some more details in the measurements provided by accelerometer sensor and makes it more accurate. Accurate enough to even detect a small change when you move your phone a little bit as well. When you shoot a 360° image, you rotates your phone in all directions and all the frames are joined with the help of data collected from Gyroscope Sensor.

Magnetometer Sensor

Used For – Used as a compass sensor to tell the directional i.e. North, South, East and West data to the Maps and other applications and also used in Metal Detector apps.

The magnetometer sensor works on the basis of hall effect, When a current carrying conductor is bought near a magnetic field, it changes the fashion in which electrons flows in the conductor resulting into voltage and current changes and hence processor comes to know what’s happening and processes accordingly.

Barometer Sensor

Used For – Measuring the distance between mean sea level and us and hence calculates, how much height we are on. Main Applications are for providing height data to Google maps to make it more precise.

Working of Barometer Sensor – It measures the atmospheric pressure to calculate the altitude from sea level. When scientist was experimenting, they found that a tube containing some liquid, keeping the open end downwards, emerged in a vessel with less height, the liquid in the tube do not matches the level of liquid of vessel. It is always above some height and find out it is atmospheric pressure which is acting upon the liquid in vessel and preventing more liquid to come out of tube. In this way, the equipment for measuring the atmospheric pressure are made.

Temperature and Humidity Sensor

Used For – Measuring the inside and atmospheric temperature. Almost all mobiles have internal temperature sensors which protects the various components inside to overheat.

Working of Temperature Sensors – Temperature Sensor is made up of two different metals. It is based on the fact that different metals behaves differently in different temperatures. The flow of electrons through them is different which makes them to flow the current through them, in different manner. By tracking the flow of current and voltage in them, the processor comes to know the measurements and processes accordingly.


Used For – Microphone is found in every single cell phone. It is used to sense the sound around the device and also helps us to talk over the phone. Some of the smartphones have two or even four microphones to minimize noise while recording video or talking over the cellphone.

The microphone consists of a diaphragm, coil and a magnet. When sound waves attacks the diaphragm, it leads to physical movement of coil or magnet which leads to change to voltage through the coil. The alternating voltage is being scanned and converted into digital voice signals.

GPS – Global Positioning System

Used For – Measurement of our location in coordinates, all over the world, to be used in Maps and other applications.

Working of GPS – There are 32 GPS Satellites (8 are Emergency) which helps us knowing our location. Other components of GPS system are Ground stations which confirms the satellites are on their right place and The receiver, the one which we have in our devices. When the receiver is connected to 4 satellites, Its accurate location can be calculated on the basis of its distance from the satellites. On the event when it cannot connect, is GPS Signal lost event which our maps usually tells us. The more satellites we are connected to, more accurate our location will be sensed.


Used For – This sensor is used to count the steps walked by the person holding the mobile phone, it is usually used in Fitness trackers.

Working of Pedometer Sensor – Pedometer Sensor is basically an accelerometer sensor which senses the linear distance covered by the device with more accuracy and converts the data into the number of steps walked, by the help of other sensors like GPS.

Heart Rate Sensor

Used For – Measurement of heart rate of a person.

Working of Heart Rate Sensor – It consists of a LED that makes the light radiations fall upon the pulses. There is a sensor which track the radiations coming back. It is based on the fact that the intensity of light radiations varies when there is a pulse. The intensity is calculated for every movement and in this way, heart rate can be calculated using a sensor.

A very few mobiles like this, do have Heart Rate sensors in them, It is commonly found in Fitness Trackers and Smartwatches.

Author: Prateek

Technology Enthusiast, Computer Science Student

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