Smartphones have gone through an incredible evolution in the last decade. We are moving to an era where our smartphones are becoming more like personal assistants, monitoring our behavior, tracking our movements and anticipating our needs. A large part of this evolution is enabled by sensor technology.
Sensors bring intelligence and awareness to our smartphones. Today’s mobile devices are packed with nearly 14 sensors that produce raw data on motion, location and the environment around us. This is made possible by the use of micro-electromechanical systems (MEMS). MEMS are mechanical systems built into tiny semiconductor chips.
Let’s take a look at some of the major sensors in the typical smartphone.
Magnetometer and GPS
Your smartphone comes equipped with a magnetometer, otherwise known as a compass. With its ability to sense magnetic fields, this MEMS device detects compass heading relative to the Earth’s magnetic north pole. In conjunction with GPS, it determines your phone’s location. GPS is another type of sensor in your mobile device. It relies on satellites to determine location. Originally developed for the military, GPS was made available for everyone in the 1980s.
Gyroscope
A three-axis gyroscope determines if your device is twisted in any direction. Using rotational force it measures angular velocity around three axes. The absolute orientation of your phone, represented as the angles yaw, pitch, and roll, is detected by a combination of the accelerometer, compass, and gyroscope.
Accelerometer
A three-axis accelerometer in your smartphone reports on how fast your phone is moving in any given linear direction. The accelerometer has the ability to detect gravity as a static acceleration as well as dynamic acceleration applied to the phone. There are various types of MEMS accelerometer hardware available, such as microscopic piezoelectric crystals that change voltage under stress when vibrations occur, or differential capacitance caused by the movement of a silicon structure. The magnetometer, GPS, gyroscope and accelerometer on your phone all work together to create the perfect navigation system.
Proximity sensor
Comprised of an infrared LED and an IR light detector, a proximity sensor detects how close the phone is to an outside object, such as your ear. This sensing is done to reduce display power consumption while you’re on a call by turning off the LCD backlight. It also disables the touch screen to avoid inadvertent touches by the cheek.
Barometer
More advanced smartphones have a chip that can detect atmospheric pressure. But to use it, the phone needs to pull down local weather data for a baseline figure on barometric pressure. What’s more, conditions inside a building, such as heating or air-conditioning flows, can affect the sensor’s accuracy. Barometers are best used in combination with other tools, including GPS, Wi-Fi and beacons.
Other sensors
Your smartphone also has an ambient light sensor to adjust brightness levels in dark environments. A fingerprint sensor can enable secure device and website authentication as well as mobile payment. Add to that list, microphone and camera sensors. Samsung’s Galaxy S6 even has an integrated heart rate monitor.
Sensors raise the consciousness of our smartphones. With mobile sensors becoming smaller and more sophisticated—and new types of sensors coming onto market—what we’re seeing today is only the beginning in the era of self-aware devices. More is waiting around the corner.
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