Testing and opening WeChat Sports to see your friends' step counts, or tilting your phone in a racing game to control the direction—these are conveniences brought by smartphones. But what components enable these functions? And what principles do they operate on?

In an era of rapid technological development, various functions of smartphones have been developed one after another, including various types of sensors installed inside the phones.

1. Ambient Light Sensor

The main function of the light sensor is to allow the phone to sense the intensity of ambient light to adjust screen brightness. This is convenient for users and saves power, thereby extending battery life.

2. Gravity Sensor

The gravity sensor operates through the piezoelectric effect. It contains a weight integrated with a piezoelectric sheet, calculating the horizontal direction through the voltage generated in two orthogonal directions.

3. Proximity Sensor

The proximity sensor emits infrared light via an infrared LED, which is received by an infrared detector after being reflected by an object. Distance is determined by the intensity of the received infrared light, controlling the screen state based on the phone's proximity to the human body.

4. Fingerprint Sensor

Capacitive fingerprint sensors are currently the mainstream technology. During operation, the finger acts as one pole of a capacitor, and the silicon chip array acts as the other. The distance between the ridges and valleys of the fingerprint and the capacitive sensor creates a capacitance difference, mapping the fingerprint pattern.

5. Accelerometer

The accelerometer uses the piezoelectric effect across three dimensions to determine the direction of acceleration. It has low power consumption but lower precision, primarily used to determine the phone's orientation.

6. Magnetic Field Sensor

The magnetic field sensor determines magnetic field strength by measuring changes in resistance. It is used for compasses and map navigation applications.

7. Gyroscope

The gyroscope measures angular velocity along one or several axes. It can track and capture all movements in 3D space, providing real and precise navigation systems, VR technology, and more.

8. GPS

The familiar GPS technology calculates the distance between the phone and satellites by comparing the timestamp of coordinates sent by satellites with the time they are received. It is used for positioning, speed measurement, distance measurement, and navigation.

9. UV Sensor

Under ultraviolet radiation, the photoelectric emission effect of metal compounds or certain semiconductors releases a large number of electrons. The intensity of UV rays can be calculated by detecting this discharge effect.

10. Barometric Pressure Sensor

The pressure sensor connects a thin film to a varistor or capacitor. When atmospheric pressure changes, it causes a change in resistance or capacitance values, providing barometric data.

11. Heart Rate Sensor

The heart rate sensor shines high-brightness LED light through the finger to capture periodic changes in blood flow to the capillaries, deriving heart contraction frequency and heart rate data.

12. Blood Oxygen Sensor

By illuminating the finger with infrared and red LED light simultaneously, the sensor measures the absorption rates of hemoglobin and oxyhemoglobin. By measuring the absorption spectrum of reflected light, it detects blood oxygen saturation.

13. Hall Sensor

Mainly based on the Hall magnetoelectric effect, when current passes through a conductor in a magnetic field, the field exerts a force on the electrons perpendicular to their movement, creating a potential difference. It is mainly used for flip-cover unlocking and screen locking functions.

Overall, more and more sensors are commonly configured in smartphones, and smart sensors with fuller functionality, smaller sizes, and higher sensitivity will continue to emerge.