what is a sensor?

Sensors can feel the measured information, and can transform the sensed information into electrical signals or other required forms of information output according to certain rules, so as to meet the requirements of information transmission, processing, storage, display, recording and control, etc. required detection device.

The existence and development of sensors allow objects to have senses such as touch, taste and smell, and make objects come alive. Sensors are the extension of human five senses. Sensors have the characteristics of miniaturization, digitization, intelligence, multi-function, systematization, and networking. It is the primary link to realize automatic detection and automatic control. The new aluminum nitride sensor can work at high temperatures up to 900°C.

Sensors can feel the measured information, and can transform the sensed information into electrical signals or other required forms of information output according to certain rules, so as to meet the requirements of information transmission, processing, storage, display, recording and control, etc. required detection device. The sensor is generally composed of four parts: sensitive element, conversion element, conversion circuit and auxiliary power supply. In order to obtain information from the outside world, people must rely on sensory organs. Therefore, it can be said that the sensor is an extension of human facial features, also known as electrical facial features.

Classification of sensors

1. Resistive

A resistive sensor is a device that converts physical quantities to be measured, such as displacement, deformation, force, acceleration, humidity, temperature, etc., into resistance values. There are mainly resistive sensing devices such as resistance strain type, piezoresistive type, thermal resistance, heat-sensitive, gas-sensitive, and humidity-sensitive.

2. Resistance strain type

The resistance strain gauge in the sensor has the strain effect of metal, that is, mechanical deformation occurs under the action of external force, so that the resistance value changes accordingly. There are two types of resistance strain gauges: metal and semiconductor. Metal strain gauges can be divided into wire type, foil type and film type. Semiconductor strain gauges have the advantages of high sensitivity (usually dozens of times that of wire and foil types) and small lateral effects.

3. Piezoresistive

The piezoresistive sensor is a device made by spreading resistance on the substrate of the semiconductor material according to the piezoresistive effect of the semiconductor material. The substrate can be directly used as a measuring sensor element, and the diffusion resistance is connected in the substrate to form a bridge. When the substrate is deformed by an external force, the resistance values will change, and the bridge will produce a corresponding unbalanced output.

The substrate (or diaphragm) materials used as piezoresistive sensors are mainly silicon wafers and germanium wafers. Silicon piezoresistive sensors made of silicon wafers as sensitive materials have attracted more and more attention, especially for measuring pressure. Solid-state piezoresistive sensors for speed and speed are most commonly used.