As already explained in the “Piezoceramic Materials” section, a
distinction is made between “soft“ and “hard“ PZT ceramics. The differences
in the parameters manifest themselves in the respective applications.
The most important fields of application of the “soft“ piezoelectric ceramics are actuators for micro- and
nanopositioning, sensors and electro-acoustic applications (sound transmitters and receivers). Advantages of the “soft“ PZT materials lie in the high piezo modulus, moderately high permittivity and high coupling
Piezoceramic actuators make use of the deformation of the piezoelectric material when an electric field is
applied. The high resolution of the change in length and large mechanical load capacity of piezoelectric
ceramic are of particular interest in high-tech fields (semi-conductors, optics and telecommunications, etc.), and also, to an increasing extent, in the automotive field (fuel injection systems), for micropumps, pneumatic valve technology and vibration damping.
Piezo Sensor Applications
Piezo sensors represent another broad area of piezoelectric applications. Apart from classical vibration recorders to detect imbalances of rotating machine parts or in crash detectors in the automotive industry, they are being used more and more in ultrasonic level measurement and flow rate measurement applications.
There, for example, the propagation time of the reflected echo of an ultrasonic wave is evaluated. Flow rate measurements are based on propagation time measurements or on the Doppler effect (measurement of phase
difference). Further typical applications of “soft“ piezo ceramics are to be found in object identification
and surveillance (e. g. surveillance sensors for cars, glass tampering detectors, etc.), sound transmitters
(buzzers) and sound receivers (microphones), to their use in the sound pickups of musical instruments.
Note: Piezorestive sensors are not classical piezo ceramic sensors but semiconducor strain gauge sensors that change resistance dependent on pressure / strain.
The most important applications of the “hard“ piezo ceramic materials are for the generation of high-powered ultrasonic waves. The advantages of these PZT materials are their moderate permittivity, piezoelectric high coupling factors, high Q-factors and very good stability under high mechanical loads and operating field strengths. Low dielectric losses facilitate their continuous use in resonance
mode with only low intrinsic warming of the component.
Practical examples of their applications can be found in the fields of
ultrasonic cleaning (typically kHz range), the machining of materials
(ultrasonic welding, bonding, drilling etc.), ultrasonic processing (e. g.
liquid dispersion), in the medical field (ultrasonic dental scale removal,
surgical instruments, etc.) and also in sonar technology. And many cannot
imagine everyday life without the familiar piezo igniters!
Piezoelectric stack actuator
Principle of flow-rate measurement (piezo sensor & actuator application)
Design principle of a composite transducer