Piezoelectric effect can be generally divided into two types, namely positive piezoelectric effect and reverse piezoelectric effect. 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 electrical polarization phenomenon occurs inside, and at the same time, charges of opposite signs are generated on some 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 a phenomenon in which the crystal is mechanically deformed by applying an alternating electric field to the crystal. Transducers manufactured by inverse piezoelectric effect are generally used for electroacoustic and ultrasonic engineering.
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.
The five basic forms of thickness deformation type, length deformation type, volume deformation type, thickness shear type, and plane shear type are the common force deformation forms of piezoelectric sensitive elements. Piezoelectric crystals are anisotropic, and not all crystals can produce piezoelectric effects in these five states. For example, quartz crystal has no piezoelectric effect of volume deformation, but has a good piezoelectric effect of thickness deformation and length deformation.
In addition to piezoelectric pressure sensors, there are also piezoresistive pressure sensors manufactured using the piezoresistive effect, strain sensors using strain effects, etc. These different pressure sensors use different effects and different materials, and can be used in different occasions. Play their unique uses.
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