Smartphone sensors – tiny enablers with a big impact
Sensors have been around since long before the smartphone. But not only did they make their way to the digital age, they are also getting smaller and smaller: The picture above shows a close-up of the intricate tech of an iPhone’s pinhead sized gyroscope.
Meanwhile, sensors are also significantly improving their accuracy. This enables your smartphone to see light and hear sound in great detail as well as picking up signals that we cannot.
And we are getting more and more creative in putting this increased perception to use. It helps to make our everyday use of technology more intuitive and opens the door to new applications. By now, your smartphone is probably also your navigation device, your camera, a gaming console and your digital wallet.
All these functions would not be possible without the microscopic sensor tech inside.
Let’s go through some of your phone’s powerful micro-sensors and see what they can do.
Motion: Accelerometer & Gyroscope
An accelerometer can detect orientation relative to gravity as well as translational motion.
Put that in your phone and you can measure tilts and translation in a linear direction to some extent. That’s how your phone knows if you are using a landscape or portrait view and can automatically adjust the screen.
To help the accelerometer out with accurate orientation, even when the phone is moving through space, its data is combined with a gyroscope. It measures changes in angular velocity.
The gyroscope is used to detect more complex orientation changes, you need for Augmented Reality apps, watching 360 degree videos or using your phone as steering wheel in a racing game.
To measure mechanical signals with digital sensors your phone uses Micro Electric Mechanical Systems (MEMS). They offer a smaller version of the concept of mechanical sensor tools embedded on an electronics board.
Here’s how it works:
Combined motion sensing with accelerometer and gyroscopes can be put to use in more complex applications. Sport and fitness apps use these sensors to track the user’s steps and combine it with GPS to show your route and pace.
Location: GPS, barometer, magnetometer
When it comes to location, the first thing that comes to mind is most likely GPS, the global positioning system. Your phone’s receiver picks up signals from a satellite network to triangulate its relative position. But since GPS signals aren’t available everywhere, more accurate positioning systems fill in the gaps with motion sensing or other sensors.
Many phones have a barometer that measures air pressure. This is useful for detecting weather changes, but in combination with other tools, like GPS, Wi-Fi and beacons, barometers can contribute altitude data to a positioning signal.
As the name indicates, a magnetometer measures magnetic fields. With the earth’s magnetic field, a magnetometer can provide your phone with a simple orientation. Digital compass apps make use of this and so do digital maps that rotate depending on your physical orientation.
But the usage of magnetometers can go beyond this: The ability to detect a magnet’s position is already working in great detail and its accuracy is improving. This paves the way for other functions like wireless gesture control.
Light & Sound: Microphones, ambient light and proximity
Microphones are not particularly new, but with Alexa, Siri and Cortana, the trend is clearly going towards voice command, giving them an increasing role in future tech.
MEMS microphones are taking over the market for smartphones since they are far smaller than any other competitor. They provide an increasingly high-definition audio quality for recordings and are standard in smart devices like smart watches or smart glasses.
Ambient light sensors can measure the light around the device. Your smartphone typically uses it to adjust the brightness level according to its environment.
The proximity sensor works in a similar way, but detects infrared light, invisible to the human eye. It is usually placed near the top speaker of your phone and combines a LED that emits an IR beam eye with a light detector. If the light gets bounced back the proximity sensor detects the reflected light.
This way it can work out whether you have the phone up to your ear or in your pocket. The screen can be switched off to save energy or disables the touch screen. Other use cases include using it as a motion detector and turn your phone into a security camera.
There are multiple ways fingerprint sensors at work: optical, capacitive or ultrasonic. These scanners use light, an electrical current or an ultrasonic pulse is and transmit it against the finger.
From the information that is pinged back they can generate an image of the ridges and valleys that make up a unique fingerprint. This technology enables features like secure login to a device or authentication for mobile payment.
The picture above shows Vivo’s first in-screen fingerprint sensor, which was demonstrated at CES 2018. It uses an optical sensor, that’s peering through the gaps between the pixels of the OLED display and allows the sensor to be put on the screen and not on the back of the device, as many other competitor products.
More to come…
Mobile sensors keep getting more accurate, more compact, and more energy-efficient. And as MEMS are becoming even smaller and more sophisticated, new types of sensors will be standard features of your phone very soon.
As new and better sensors make your phone more perceptive than ever, opportunities for their potential application are unfolding: Immersive gaming experiences, indoor navigation and new security standards might be just a micrometre sensor away.