Last Updated on April 22, 2023 by You Ling
Piezoelectric ultrasonic sensors are an important application of sensors. The article introduces the knowledge related to piezoelectric ultrasonic sensors, hoping to help you
- What is a piezoelectric sensor
- Classification of piezoelectric sensors
- What is a piezoelectric ultrasonic sensor
- Working principle of piezoelectric ultrasonic sensor
- Application of piezoelectric ultrasonic sensors
1、What is a piezoelectric sensor?
A piezoelectric sensor is a type of sensor based on the piezoelectric effect. It is a self-generating and electromechanical transducer. Its sensitive element is made of piezoelectric material, which produces a surface charge when subjected to force. This charge becomes an electrical output proportional to the external force after being amplified and impedance-transformed by a charge amplifier and a measuring circuit, respectively. Piezoelectric sensors are often used for flexible motion, touch, vibration, and shock measurements. They can be used in various fields such as medical, aerospace, consumer electronics, and nuclear instrumentation.
2、Classification of piezoelectric sensors:
There are roughly four types:
Piezoelectric force sensors
Piezoelectric pressure sensors
Piezoelectric acceleration sensors
Polymer pressure sensors
3、What is a piezoelectric ultrasonic sensor?
An ultrasonic sensor is a sensor that converts ultrasonic signals into other energy signals (usually electrical signals). Ultrasonic waves are mechanical waves with vibration frequencies higher than 20 kHz. They have the characteristics of high frequency, short wavelength, small diffraction phenomenon, especially good directionality, and can be oriented and propagated as a ray. Ultrasonic waves have great penetrating power for liquids and solids, especially in opaque solids. Ultrasonic waves will produce significant reflection echo when encountering impurities or interfaces and can generate Doppler effects when encountering moving objects. Ultrasonic sensors are widely used in industry, defense, and biomedical fields.
4、Working principle of piezoelectric ultrasonic sensor:
Ultrasonic waves are a type of mechanical oscillation in elastic media and have two forms: transverse oscillation (transverse wave) and longitudinal oscillation (longitudinal wave). The longitudinal oscillation is mainly used in industrial applications. Ultrasonic waves can propagate in gases, liquids, and solids, with different propagation speeds. In addition, they also have refraction and reflection phenomena and attenuate during propagation. Ultrasonic waves have lower frequencies, usually several tens of kHz, when propagated in air, while they can have higher frequencies when propagated in solids and liquids. Ultrasonic waves attenuate quickly when propagated in air but less so when propagated in liquids and solids, allowing for longer propagation distances. By utilizing the characteristics of ultrasonic waves, various ultrasonic sensors can be developed, and with different circuits, various ultrasonic measuring instruments and devices can be made, and are widely used in communications, medical devices, and home appliances.
Piezoelectric crystal-based ultrasonic sensors are reversible sensors that can convert electrical energy into mechanical vibration to produce ultrasonic waves, and can also convert ultrasonic waves into electrical energy when receiving them. Therefore, they can be divided into transmitters or receivers.
5、Application of piezoelectric ultrasonic sensors:
Ultrasonic sensors can detect the status of a container. By installing an ultrasonic sensor at the top of a plastic melt tank or plastic pellet chamber and emitting sound waves into the container, the status of the container, such as full, empty, or half full, can be analyzed.
Ultrasonic sensors can be used to detect transparent objects, liquids, materials with any surface roughness, smoothness, light density, and irregular objects. However, they are not suitable for outdoor, hot environments, pressure tanks, or foam objects.
Ultrasonic sensors can be used in food processing plants to realize a closed-loop control system for plastic packaging inspection. In combination with new technologies, they can work well in humid environments such as bottle washers and noisy environments.