Pressure sensor based on piezoelectric effect. It has many types and models, and can be divided into two types: diaphragm type and piston type according to the form of elastic sensitive components and force-bearing mechanism.
Introduction
Most piezoelectric pressure sensors are made using the positive piezoelectric effect. The positive piezoelectric effect refers to: when the crystal is subjected to an external force in a certain direction, an internal polarization phenomenon occurs, and at the same time, charges of opposite signs are generated on a certain two surfaces; when the external force is removed, the crystal returns to the uncharged State; when the direction of the external force changes, the polarity of the charge changes accordingly; the amount of charge generated by the crystal force is proportional to the size of the external force. The inverse piezoelectric effect, also known as the electrostrictive effect, refers to the phenomenon of mechanical deformation of a crystal caused by applying an alternating electric field to the crystal. Transducers manufactured by inverse piezoelectric effect are generally used for electroacoustic and ultrasonic engineering.
Pressure sensor based on piezoelectric effect. It has many types and models, and can be divided into two types: diaphragm type and piston type according to the form of elastic sensitive components and force-bearing mechanism. The diaphragm type is mainly composed of a body, a diaphragm and a piezoelectric element (see figure). The piezoelectric element is supported on the body, the measured pressure is transmitted to the piezoelectric element by the diaphragm, and then the piezoelectric element outputs an electrical signal that has a certain relationship with the measured pressure (see piezoelectric sensor). The characteristics of this sensor are small size, good dynamic characteristics, high temperature resistance and so on. Modern measurement technology places increasingly higher requirements on the performance of sensors. For example, a pressure sensor is used to measure the internal combustion engine dynamometer, water cooling is not allowed during the measurement, and the sensor is required to withstand high temperature and small volume. Piezoelectric materials are most suitable for the development of such pressure sensors. A more effective method is to choose a quartz crystal cutting method suitable for high temperature conditions, for example, XYδ (+ 20 ° ～ + 30 °) cut quartz crystal can withstand 350 ℃ high temperature. The LiNbO3 single crystal has a Curie point of up to 1210 ° C, making it an ideal piezoelectric material for manufacturing high-temperature sensors.
Application
Piezoelectric pressure sensors are widely used in biomedical measurement. For example, ventricular catheter microphones are made of piezoelectric sensors. Piezoelectric pressure sensors are often used for dynamic pressure, so the application of piezoelectric pressure sensors is very wide.