The realization of piezoelectric effect in piezoelectric pressure sensors is a complex and delicate process, which is based on the polarization phenomenon of some dielectrics when they are subjected to external forces.
1. Basic principle of piezoelectric effect
Piezoelectric effect means that when some dielectrics are deformed by external force in a certain direction, their interior will be polarized, and at the same time, positive and negative charges will appear on their two opposite surfaces. When the external force is removed, it will return to its uncharged state. This phenomenon is called the positive piezoelectric effect. On the contrary, when an electric field is applied in the direction of polarization of dielectrics, these dielectrics will also deform, and when the electric field is removed, the deformation of dielectrics will disappear, which is called the inverse piezoelectric effect.
2. Application of piezoelectric effect in piezoelectric pressure sensor
Conversion of pressure to charge:
In piezoelectric pressure sensors, the sensitive elements are usually made of piezoelectric materials, such as quartz, barium titanate and so on. When these piezoelectric materials are subjected to external pressure, they deform mechanically.
This deformation leads to the relative transfer of positive and negative charge centers in the piezoelectric material, resulting in polarization.
The result of the polarization phenomenon is the appearance of bound charges of opposite sign on the two opposite surfaces of the piezoelectric material, that is, a potential difference is created.
Amplification and conversion of charge:
The amount of charge generated is proportional to the magnitude of the measured pressure, so the pressure can be measured indirectly by measuring the amount of charge.
However, since the amount of charge generated by the piezoelectric effect is usually small, a charge amplifier is needed to amplify these charge signals.
The amplified charge signal is further converted by the measuring circuit into an electrical output proportional to the external force, such as a voltage or current signal.
Display and recording of signals:
The amplified and converted electric quantity output can be connected to a display or recording instrument to monitor or record the change of the measured pressure in real time.
In this way, the piezoelectric pressure sensor can convert the mechanical pressure into an electrical signal and realize the accurate measurement of the pressure.
3.Characteristics and Advantages of Piezoelectric Pressure Sensor
Small size and light weight: Piezoelectric pressure sensors usually have small size and light weight, which is easy to install and use.
High frequency response: Piezoelectric pressure sensors can be used to measure high frequency signals due to the fast response of the piezoelectric effect.
High signal to noise ratio: The piezoelectric pressure sensor has a relatively low noise in the measurement process, so it has a high signal to noise ratio.
High temperature resistance: Some piezoelectric materials (such as quartz) have high temperature resistance, so that piezoelectric pressure sensors can work in high temperature environment.
To sum up, the piezoelectric effect in the piezoelectric pressure sensor is reflected by the deformation of the sensitive element, the generation and amplification of the charge, and the display and recording of the signal. This process enables the piezoelectric pressure sensor to convert mechanical pressure into electrical signals and achieve accurate measurement of pressure.
