Basic principles of piezoelectric ceramics sensors

Piezoelectric ceramics sensors are ultrasonic sensors made by using the piezoelectric effect produced by certain dielectrics. The so-called piezoelectric effect refers to the phenomenon that certain dielectrics undergo deformation (including bending and stretching deformation) due to the polarization of internal charges when they are deformed by external forces in a certain direction. Piezoelectric materials can be divided into piezoelectric single crystal,piezoelectric polycrystalline and organic piezoelectric materials.

The most commonly used piezoelectric ceramics transducer are various types of piezoelectric ceramics belonging to piezoelectric polycrystals and quartz crystals in piezoelectric single crystals. Other piezoelectric single crystals include lithium niobate, lithium tantalate, lithium gallate, and bismuth germanate suitable for high-temperature radiation environments.　　

The working principle of the piezoelectric ceramics sensor is mainly based on the piezoelectric effect. It uses electrical components and other machinery to convert the pressure to be measured into electricity, and then performs measurement precision instruments such as many pressure transmitters and pressure sensors. Piezoelectric ceramics sensors cannot be used in the static measurement, because the charge after being subjected to external force can be preserved when the circuit has infinite input resistance.

Actual piezo acoustic sensors can only be used in dynamic measurements. Its main piezoelectric materials are dihydrogen phosphate, sodium potassium tartrate and quartz. The piezoelectric effect is found on quartz. When the stress changes, the electric field changes very little, and some other piezoelectric crystals will replace quartz. Potassium sodium tartrate, it has a large piezoelectric coefficient and piezoelectric sensitivity, but it can only be used indoors where the humidity and temperature are relatively low.

　Dihydrogen phosphate is an artificial crystal, it can be used in high humidity and high temperature environment, so its application is very wide. With the development of technology, the piezoelectric effect has also been applied to polycrystals. For example: piezoelectric ceramics, niobate magnesium acid piezoelectric ceramics, niobate series piezoelectric ceramics and barium titanate piezoelectric ceramics are all included. Piezoelectric effect sensor is electromechanical conversion type and self-generation type sensor. Its sensitive components are made of piezoelectric materials. When the piezoelectric materials piezoelectric cylinder transducers are subjected to external force, charges will be formed on its surface. The charges will pass through the charge amplifier, the amplification of the measuring circuit, and the impedance conversion. It is converted into a power output proportional to the external force received.