Sensor is a kind of detection device, which is defined as: A device or device that can sense the specified device to be measured and convert it to a usable signal according to a certain rule, usually consists of the sensor and the conversion device. The sensor can fulfill the multiple requirements of information transmission, processing, storage, display, recording and control, and has the functions of miniaturization, digitization and intelligence. It is the first loop to realize automation.

Sensor generally consists of sensitive components, conversion components, conversion circuits, auxiliary power supply four parts, as shown below. Among them, the sensor receives the measurement directly, which is used to output the signal related to the physical quantity to be measured. The sensor mainly includes thermal, light, moisture, gas, force, sound, magnetism, And other ten categories; the conversion element is used to convert the physical components of the sensor output signals into electrical signals;

The conversion circuit is used to amplify and modulate the output electrical signal of the conversion element. The auxiliary power supply is used to provide energy to the system (mainly the sensitive element and the conversion element).

There are many applications of sensors: gravity sensors, almost perfect in games such as Need for Speed and Parkour, etc. Acceleration sensors and mobile phone shake functions are used to sense the acceleration of mobile phones. Light sensors and automatic dimming of mobile phones Function; distance sensor, pick up the phone to leave the ears screen brighter, the phone close to the ears black screen. There are numerous sensors in cell phones, especially many of them using sensors.