5.4.7.4 Actuators

In the precision engineering applications, precise linear or rotational movements are required for achieving technological perfection. In piezoelectrics, application of high electric fields (without using oscillations) correspond to only tiny changes in the crystal dimension and these changes can be very precise, achieving better than a micrometer  precision. This ability makes these materials useful as precise actuators for achieving very precise motions.

In these applications, typically multilayer ceramics consisting of layers thinner than 100 microns, are used. One can achieve very high field in the multilayered materials using voltages lower than 150-200 V, not very high voltages.

You can have it in two forms:

• Direct Piezo Actuators with strokes lower than 100 microns or so and

• Amplified Piezoelectric Actuators which can yield millimeter long strokes.

Some of the examples of applications are

• Piezoelectric motors consisting of piezoelectric elements which apply a directional force to an axle, causing it to rotate. As the distances travelled are extremely small, it is a very high-precision replacement for the conventional stepper motor.

• Scanning force microscopes use inverse piezoelectric effect to keep the sensing needle close to the probe

• Laser mirror alignment in the laser electronics helping maintain accurate optical conditions inside the laser cavity to optimize the beam output.

• Loudspeakers: Voltage is converted to mechanical movement of a piezoelectric polymer film.

• In inkjet printers where piezoelectrics are used to control ink flow from the print head to the paper.

• As fuel injectors in diesel engines in place of commonly used solenoid valve devices.