Piezoelectric rings are mainly found in ultrasound applications, but they are also involved in sensor and actuator technologies. The type of application and the performance depend on the choice of piezoceramic material. This enables a wide range of uses from medical to industrial. In addition, these compact components are able to generate high power ultrasound and they can be produced in various designs and sizes. Thin piezo rings are used, for example, in membrane nebulizers for generating the finest of medication droplets for inhalation by patients with respiratory disorders.
Rings provide a decisive benefit over disks: They can be fixed on tensioning screws to achieve mechanical preload. The preload in fixed systems is necessary for the individual rings to remain connected to each other throughout the movement.
It is also possible to further refine individual rings or combine several piezo rings to form transducer elements. Especially in assembling power ultrasonic transducers, piezo rings are energy-efficient, compact, and versatile components. Depending on the design, torsional movements can also be implemented in addition to longitudinal displacements.
Customized Versions on Request
With more than thirty years of expertise in the development and production of piezoceramics, PI Ceramic offers end-to-end service extending from the selection of the suitable material through to the development of application-based solutions. The dimensions of the piezo rings can be chosen from within the range of specifications. Outer and inner diameters and the thickness of the components depend on the specifications required.
In addition to screen printing and sputtering, there is also the option of coating with chemical nickel. For chemical nickel, layer thickness is between 1 and 5 µm. Depending on the dimensions, piezoceramic rings can be manufactured from various soft and hard PTZ >> materials. Hard materials are suitable for applications in the fields of power ultrasound and sonar; soft materials, in contrast, are suitable for use in various areas of sensor technology, actuator technology, and aerial ultrasound. >> Lead-free materials can be used for application-specific developments. Likewise, non-magnetic variants for field strengths > 1 T are also available as well as the manufacturing of stacked ring actuators.
Bismuth-sodium-titanat (BNT) and potassium sodium niobate (KNN) provide lead-free alternatives to our PZT materials that are already being used in applications, such as ultrasonic transducers, motors, ultrasonic sensors, and mesh nebulizers. As the properties of the lead-free materials deviate from those of PZT, it is necessary to perform a suitability test for every inquiry. We will be happy to advise on deployment in your specific application.
The use of piezoceramic rings as sensors follows the principle of the direct piezoelectric effect. Whenever a mechanical load, such as pressure or ultrasound, is exerted on the ceramics, the piezo component generates an electric signal. When used as an actuator, on the other hand, the displacement of the piezo ring is generated when a voltage is applied. This might be a deformation caused by direct current or a vibration, for example in the ultrasonic range, caused by alternating voltage. Depending on the design of the piezo components, it is possible to achieve displacements in a longitudinal, radial, torsion, or shear direction. The strength of the displacement is determined by the size of the piezo rings as well as the voltage applied.
For rings with a positive polarization direction at the top and a negative one at the bottom, there are the following displacement directions:
Whenever there is a longitudinal displacement (d33 effect), a smaller deformation is always also generated in a radial direction (d31 effect).
To reach certain frequencies in the longitudinal vibration mode, it is necessary to change the ring thickness. For frequencies in a radial direction, their diameters have to be adjusted. The following applies for both variants: The larger they are, the smaller the frequency.
Shear rings and torsion rings require a special production path. Depending on the design, the following displacements are possible:
To achieve a torsion movement of the rings, they are subdivided into segments and the segments are polarized individually. After gluing, a shear displacement occurs in every segment, which, combined, leads to a torsion movement of the ring.
Rings with Special Electrodes
Alongside full-surface electrodes made of thin films and thick films, further electrode designs can be implemented. For example, wrap-around contacts for applying electric contact at a favorable position are feasible. Furthermore, it is possible to produce piezo rings with segmented or lateral electrodes. The inner and outer insulating edge can also be enlarged within freely selectable limits.
The Fields of Application of Piezoceramic Rings
Support for medical technology applications, such as:
- Mesh nebulizers
- Dental scalers
- Phacoemulsification
- Ultrasonic scalpels
- Sample preparation & cell lysis
- Ultrasonic atomization
- Welding, drilling, and cutting
- Ultrasonic cleaning
- Precision positioning
- Sensor devices
- Non-destructive testing
- Precision dosing
- Hydro acoustics
Downloads
Material Data
Lead-Free Piezoceramic Materials
User Manual A000T0047
Handling and Electrical Contacting of Piezo Components