- What is a transducer
- What is a piezoelectric transducer
- History of piezoelectric transducers
- Types of piezoelectric transducers
- Applications of Piezoelectric Transducers
- How to choose the appropriate piezoelectric transducer
- Development trend of piezoelectric transducers
1、What is a transducer?
A device that converts one form of energy such as electrical, mechanical, or sound energy into another form is called a transducer, also known as an active sensor. The main performance indicators of a transducer include operating frequency, bandwidth, electroacoustic frequency, impedance at resonance frequency, directionality (transmitting beamwidth), and sensitivity. Transducers are mainly classified into two categories: magnetostrictive and piezoelectric crystals.
2、What is a piezoelectric transducer?
A piezoelectric transducer is a device made using the positive and negative piezoelectric effects of piezoelectric materials. As the name implies, a transducer is a device that can convert energy. Piezoelectric transducers are devices that use the piezoelectric effect of certain single-crystal materials and the electrostriction effect of certain polycrystalline materials to convert electrical energy into sound energy and vice versa. Due to their high electroacoustic efficiency, large power capacity, and the ability to design them according to different applications based on their structure and shape, they are widely used in the field of high-power ultrasound.
3、History of piezoelectric transducers
In 1917, Langer and Wan designed a sandwich-type transducer for underwater detection. This transducer was made using quartz crystals as piezoelectric materials and was sandwiched between two steel plates. The laminated magnetostrictive transducer, which appeared after 1933, quickly replaced Langer and Wan's transducer due to its high strength, good stability, and large power capacity. In the 1950s, the successful development of electrostrictive materials, lead zirconate titanate ceramic, and zirconium titanate piezoelectric ceramic, caused the Langer and Wan-type ultrasonic transducer to rise again. Currently, piezoelectric ultrasound has a wide range of applications, and the requirements for ultrasound measurement accuracy, measurement range, ultrasound power, and device miniaturization are increasingly higher.
4、Types of piezoelectric transducers
Element shape
According to the shape of the piezoelectric element that makes up the transducer, it is divided into thin plate, circular, annular, cylindrical, rod, thin shell sphere, and piezoelectric film.
Vibration mode
According to the vibration mode, it is divided into extensional vibration, bending vibration, torsional vibration, etc.
Vibration direction
According to the direction of extensional vibration, it is divided into thickness, tangential, longitudinal, radial, etc.
Piezoelectric conversion method
According to the piezoelectric conversion method, it is divided into transmitting type (electric-sound conversion), receiving type (sound-electric conversion), and dual-use type.
5、Applications of Piezoelectric Transducers
Piezoelectric transducers have a wide range of applications. They can be classified according to the industry into industrial, agricultural, transportation, daily life, medical, and military sectors. They can also be classified according to their functions, such as super processing, ultrasonic cleaning, ultrasonic detection, testing, monitoring, remote control, etc. They can be used in various environments, such as liquids, solids, gases, and biological tissues. They can also be classified according to their properties, such as power ultrasonic, testing ultrasonic, ultrasonic imaging, etc.
Ultrasonic waves are generated by converting high-frequency electrical energy into mechanical vibration through transducers. The performance and service life of the transducers with the same size and shape depend on the material selection and manufacturing process. High-power ultrasonic transducers are commonly used in ultrasonic plastic welding machines, ultrasonic metal welding machines, various handheld ultrasonic tools, continuous ultrasonic emulsifiers, atomizers, ultrasonic engraving machines, and other equipment.
6、How to choose the appropriate piezoelectric transducer:
6.1 Sensitivity:
Refers to the efficiency of the transducer's conversion ability. High sensitivity indicates high conversion efficiency.
6.2 Resonant frequency:
Refers to the frequency at which the transducer resonates.
6.3 Directivity:
Refers to the intensity of the emission or reception pattern of the transducer's radiating surface in various directions.
6.4 Temperature resistance:
Refers to the upper and lower temperature limits at which the transducer can operate normally.
6.5 Pressure resistance:
Refers to the upper and lower pressure limits at which the transducer can operate normally.
6.6 Electrical parameters:
Refers to the transducer's own impedance, capacitance, inductance, etc.
6.7 Amplitude:
Refers to the vibration amplitude of the transducer under a fixed driving voltage.
6.8 Voltage limit:
The maximum voltage value of the transducer. Long-term voltage exceeding this value can easily cause depolarization of the piezoelectric ceramic.
6.9 Sealing:
Refers to the sealing performance of the transducer in liquid.
6.91 Corrosion resistance:
Refers to the transducer's resistance to corrosive environments.
7、Development trend of piezoelectric transducers:
Piezoelectric transducers are key components of many brakes and are increasingly widely used. Research on them is very active internationally.
The current development direction of piezoelectric transducers is high power, low voltage drive, high frequency, thin film, miniaturization, and integration.
