What are physical sensors? How to distinguish them?

There are many types of sensors, and sensors can also be classified in different ways. One type is to distinguish sensors based on the purpose of measurement. In this way, sensors can be divided into physical sensors, chemical sensors, etc. Physical sensors can be divided into structural sensors and physical sensors.

Structural sensors are based on structures (such as shape, size, etc.), and use certain physical laws to sense (be sensitive to) the measured value, and convert it into electrical signals to achieve measurement. For example, a capacitive pressure sensor must have a capacitive sensitive element designed and made according to specified parameters. When the measured pressure acts on the moving electrode of the capacitive sensitive element, the change in the capacitor gap causes the change in the capacitance value, thereby achieving the measurement of pressure.

Physical sensors are sensors that use the inherent characteristics and effects of certain functional materials to sense (be sensitive to) the measured value and convert it into a usable electrical signal. For example, a thermocouple temperature sensor works using the thermoelectric effect. Weld two conductors or semiconductors A and B of different materials together to form a closed loop. When there is a temperature difference between the two attachment points 1 and 2 of conductors A and B, an electromotive force is generated between the two, thus forming a current of varying magnitude in the loop. This phenomenon is called the thermoelectric effect.

Generally speaking, physical sensors have certain requirements for physical effects and sensitive structures, but with different emphases. Structural sensors emphasize that they must rely on precisely designed and manufactured structures to ensure their normal operation; while physical property sensors mainly rely on the physical properties and physical effects of the material itself to achieve sensing of the measured value. In recent years, due to the rapid development and progress of materials science and technology, physical sensors have become more and more widely used.