Sensor is a kind of detection device that can sense the measured information, and can convert the sensed information into electrical signals or other required forms of information output according to certain rules to meet the requirements of information transmission, processing, storage, display, recording and control.

The characteristics of sensors include miniaturization, digitalization, intelligence, multifunction, systematization and networking. This is the first step to realize automatic detection and automatic control. The existence and development of sensors make objects have senses such as touch, taste and smell, and make them come alive slowly. Generally, according to its basic sensing function, it can be divided into ten categories: heat sensitive element, light sensitive element, gas sensitive element, force sensitive element, magnetic sensitive element, humidity sensitive element, sound sensitive element, radiation sensitive element, color sensitive element and taste sensitive element.