Smartphones today come with a wealth of sensors to facilitate a better user experience, provide apps with enhanced information about the world around the phone and provide robust and increased battery life.

Proximity Sensor

Detects when an object is near to the phone. Most commonly used to sense when a phone is held up to the users ear to turn off the display. This saves both battery life and prevents accidental screen touches.

Accelerometer and gyroscope

Accelerometers in mobile phones are used to detect the orientation of the phone. The gyroscope, or gyro for short, adds an additional dimension to the information supplied by the accelerometer by tracking rotation or twist.

An accelerometer measures linear acceleration of movement, while a gyro on the other hand measures the angular rotational velocity. Both sensors measure rate of change; they just measure the rate of change for different things.

In practice, that means that an accelerometer will measure the directional movement of a device but will not be able to resolve its lateral orientation or tilt during that movement accurately unless a gyro is there to fill in that info.

With an accelerometer you can either get a really “noisy” info output that is responsive, or you can get a “clean” output that’s sluggish. But when you combine the 3-axis accelerometer with a 3-axis gyro, you get an output that is both clean and responsive in the same time.”

Accelerometers are also used to provide ‘steps’ information for a vendors ‘health’ application.

Digital compass

The digital compass that’s usually based on a sensor called the magnetometer and provides mobile phones with a simple orientation in relation to the Earth’s magnetic field. As a result, your phone always knows which way is North so it can auto rotate your digital maps depending on your physical orientation.

GPS

Global Positioning System (GPS) units in smartphone communicate with the satellites to determine our precise location on Earth. The GPS technology doesn’t actually use internet data this is why we can find our location on maps even after losing the signals, but the map itself is blurry as it requires internet to load the details — this is how offline map works. GPS is used in all location-based apps like Uber and Google Maps.

The accelerometer, gyroscope, magnetometer, and GPS work together to create the perfect navigation system in your smartphone.

Ambient Light Sensor

The light sensor detects the lighting levels in the vicinity to adjust the display brightness accordingly. It is used in Automatic Brightness Adjuster to decrease or increase the brightness of the smartphone screen based on the availability of light.

Microphone

The microphone is basically a sound sensor that detects and measures the loudness of sound. While there are different types of microphone sensors available, smartphones generally use micro-sized electret microphones.

Apart from making and receiving calls, it is used for voice search and voice commands for digital assistant apps like Google Assistant, Siri, Cortana, etc.

Touchscreen Sensors

The smartphone sensors in a touchscreen have an electrical current passing through them at all times and touching the screen causes a change in the signals. This change acts as input for the device. Before Apple introduced the capacitive touchscreen, resistive screens were used in the display. But nowadays, the capacitive screen is used in almost all smartphones.

Fingerprint Sensor

Gone are the days of memorizing passwords and patterns to unlock your phone as many users prefer using the fingerprint scanner these days. Fingerprint sensor enables biometric verification to secure many smartphones today. It is a capacitive scanner that records your fingerprint electrically.

When you put your finger on its surface, the ridges in your fingerprints touch the surface whereas the hollows between the ridges have a slight separation. In short, it measures the varying distances and pattern between the ridges on the surface of your finger. This smartphone sensor is quite useful in apps that require authentication such as mobile payment apps.

Pedometer

The pedometer is used for counting steps, and fitness tracker makes use of this sensor to count the number of steps you take. Pedometers generally use the values generated by the accelerometer to monitor your movements like running or walking.

Barcode/QR Code sensors

Most of the smartphones have barcode sensors that can read a barcode by detecting the reflected light from the code. It generates an analog signal with varying voltage that represents the barcode. This analog signal is then converted to a digital one and finally decoded to reveal the information in it. Barcode sensors are useful in scanning the barcodes products or QR codes.

Barometer

There are many high-end Android phones like Pixel and iPhones that include a barometer in their hardware. The barometer measures the air pressure, so it is quite useful in detecting weather changes and in calculating the altitude you’re at.

Heart Rate Sensor

Next up is the heart rate sensor that measures heartbeat with the help of LED and optical sensors. The LED emits light towards the skin, and this smartphone sensor looks for the light waves reflected by it.

There is a difference in the light intensity when there is a pulse. The heartbeat is measured by counting the changes in light intensity between the minute pulsations of the blood vessels. Many fitness and health apps use this method to calculate the heart rate.

Thermometer

Every smartphone comes with an inbuilt thermometer for monitoring the temperature inside the device and battery. In case a component starts overheating, the system shuts down itself to prevent any damage.

However, some handsets come with additional thermometers to measure ambient temperature. If you can recall, the Samsung Galaxy S4 bragged of thermometer that can measure temperature. Such thermometer sensors can be used by apps to detect your room temperature.

Air Humidity Sensor

Now that we are talking about Galaxy S4 let’s discuss the Air Humidity sensor as well. S4 was the first smartphone to incorporate an air humidity sensor. It could measure the humidity in the air, and the data collected by it would tell the user whether the given air temperature and humidity are optimum or not. But again, this type of sensor is used by selected handsets only.

Geiger Counter

Now, this is one smartphone sensor that you should not expect to find in common devices. In fact, there is only one phone that supports it – the Sharp Pantone 5. This handset has been released in Japan only. The Geiger Counter in it can measure the current radiation level in the area.

Final Words

There is so much of technology packed into our phones that we often take them for granted. But these are some of the most important smartphone sensors that you should know of. Given that smartphones are getting smarter day by day and sensors play a major role in it, this list is will definitely grow longer and I will keep adding more to it. In case there is a smartphone sensor I forgot to mention in this article, do let us know in the comment section below!